kendriya vidyalaya · · 2018-01-265x 7 3x 4 f x ... ans. c 3. a particle ... (ans. max value = 4...
TRANSCRIPT
KENDRIYA VIDYALAYA DANAPUR CANTT
MINIMUM PROGRAMME FOR
AISSCE – 2018
SUBJECT : MATHEMATICS
(CLASS – XII)
Prepared By :
K. N. P. SinghVice-Principal
K.V. Danapur Cantt
(2) XII/Maths.
MATRIX
1. Find X and Y if
211
123y2x&
437
744yx2
2. If ,
363
121
484
X
3
1
4
, find X (Ans. X = [–1 2 1]
3. Find x such that 0
x
2
1
2315
152
231
1x1
(Ans. x = –14 or –2)
4. If
11
43A then Prove that NnV
n21n
n4n21An
5. If 213B&
7
5
1
A
verify that (AB)' = B'A'
6. Express the Matrix
564
386
531
as the sum of a symmetric and skew symmetric
Matrix.
7. Using elementary row transformation find the inverse of Matrix
102
114
123
.Ans
542
752
321
8. Show that
42
58A satisfies the equation x2 + 4x – 42 = 0. Hence find A–1
Ans.
82
54
421
9. If
321
213
812
A show that A (adjA) = (adj A) A = |A| I3
10. Using Matrix method, solve the following system of linear equations :
11z4y3x3
2z2y3x2
4z3y2x
(Ans. x = 3, y = –2 & z = 1
(3) XII/Maths.
DETERMINANT
1. Evaluatecbbaac
baaccb
accbba
2. Using properties of determinant prove that :
(i) xzzyyxxyz
zyx
zyx
zyx
333
222
(ii)
222
(iii)
zyx
rqp
cba
2
yxxzzy
qpprrq
baaccb
(iv) 3cba
bacc2c2
b2acbb2
a2a2cba
(v)
c1
b1
a1
1abc
c111
1b11
11a1
(vi) 322
22
22
22
ba1
ba1a2b2
a2ba1ab2
b2ab2ba1
(vii) cbaaccbba
cba
cba
111
333
(viii)
333
222
111
(ix) If x, y, z are different and
0
z1zz
y1yy
x1xx
A32
32
32
, then show that 1+ xyz = 0
(4) XII/Maths.
RELATION & FUNCTIONS
1. Prove that the relation R on the set N × N defined by (a, b) R (c, d) a + d = b + c
V (a, b), (c, d) N × N is an equivalance relation.
2. Consider the set N × N, the set of all ordired pairs of natural numbers. Let R be
the relation in N × N which is defined by (a, b) R (c, d) if and only if ad = bc. Prove
that R is an equivalence relation.
3. Prove that the relation R on set Z of all integers defined by (a, b) R (a – b) is
divisible by 5 is an equivalence relation on Z.
4. Show that the function f : R R given by f (x) = ax + b, a, b r, a o is a
bijection.
5. Show that the function f : R – {–1} R – {1} given that 1x3x
xf
is a bi jective
function.
6. Let f : R+ [-5, ] given by f (x) = 9x2 + 6x – 5. Show that f is invertible and
3
16yyf 1
7. Let A be the set of all real numbers except – 1
Let an operation * be defined on A as a * b = a + b + ab V a, b A
Prove that (i) A is closed under the given operation
(ii) * is commutative as well as associative
(iii) the number O is the identity element
(iv) every element a A hasa1
a
as inverse
8. Let
53
R57
R:f be defined as 7x54x3
xf
and
57
R53
R:g
be defined as 3x54x7
xg
Show that fog = IA and gof = IB where IA and IB are idnetity functions on A and B
respectively.
(5) XII/Maths.
INVERSE TRIGONOMETRIC FUNCTIONS
1. Find the value of
21
sin21
cos1tan 111
1213
632
4.Ans
2. Find the value of 3coteccos2tansec 1212 (Ans. 15)
3. Prove that
1731
tan71
tan21
tan2 111
4. Prove that tan–1 1 + tan–1 2 + tan–1 3 =
5. Prove that47
1tan
31
tan2 11
6. Prove that48
1tan
71
tan51
tan31
tan 1111
7. Prove thatab2
ba
cos21
4tan
ba
cos21
4tan 11
8. Prove that [4
,0]x,2x
xsin1xsin1
xsin1xsin1cot 1
9. Prove that 21
22
221 xcos
21
4x1x1
x1x1tan
10. If cos–1x + cos–1y + cos–1z = Prove that x2 + y2 + z2 + 2xyz = 1
11. If tan–1x + tan–1y + tan–1z = Prove that x + y + z = xyz
12. (a) Solve : 4
x3tanx2tan 11
61
x.Ans
(b) Solve : 2 tan–1 (cos x) = tan–1 (2 cosec x)
4
x.Ans
13. Solve :42x
1xtan
2x1x
tan 11
2
1.Ans
14. Write
x1x1
tan2
1 in the simplest form.
15. Write
xsin1xcos
tan 1 in the simplest form.
(6) XII/Maths.
CONTINUITY & DIFFERENTIABILITY
1. A function f is defined by
3x23x2
2x1,1xxf
Find whether f is continuous at x = 2 (Ans. continuous)
2. A function f is defined by
0x5x
1xxxf
2
Show that the function is discontinuous at x = 1.
3. Discuss the continuity of the function
0x,
21
0x,x
xcos1
xf2
at x = 0
4. For what value of k is the function
2xif1x3
2xifk
2xif1x2
xf continuous at x = 2 ?
(Ans. k = 5)
5. Find the value of k if f (x) is continuous at2
x , where
2x,3
2x,
x2xcosk
xf
(Ans. k = 6)
6. If the function
1xifb2ax5
1xif11
1xifbax3
xf is continuous at x = 1, find the values
of a & b. (Ans. a = 3 & b = 2)
7. For what value of k,
0x,k
0x,x8
x4cos1xf 2 is continuous at x = 0 ? (Ans. k = 1)
8. Prove that f (x) = |x| is continuous at x = 0 but not differentiable at x = 0
(7) XII/Maths.
DIFFERENTIATION
Find the derivative w.r. to x of the following :
1.
xsinxcosxsinxcos
tan 1 (Ans. 1)
2.
xsinaxcosbxsinbxcosa
tan 1 (Ans. –1)
3.
x1x1
tan2
1
2x121
.Ans
4.
22
221
x1x1
x1x1tan
4x1
x.Ans
5.
13x112x5
sin2
1
2x1
1.Ans
6. If
xsin1xsin1
xsin1xsin1coty 1 Prove that
dxdy
is independent of x.
7. If sin y = x sin (a + y) Prove that asin
yasindxdy 2
8. If t1sinax
and t1cosay
Prove that 0xy
dxdy
9. If y = tan–1 x show that 0dxdy
x2dx
ydx1 2
22
10. If 22 axxlogy Prove that 0dxdy
xdx
ydax 2
222
11. If n2 1xxy Prove that (x2 + 1) y2 + xy1 – n2 y = 0
12. If y = A cos n x + B sin n x Prove that 0yndx
yd 22
2
13. If y = a cos (log x) + b sin (log x) prove that 0ydxdy
xdx
ydx 2
22
14. If y = sin (m sin–1x) show that (1 – x2) y2 – xy1 + m2y = 0
15. If y = xsinx + (sinx)x finddxdy
16. If
...xxxxy, then prove that xlogy1x
ydxdy 2
(8) XII/Maths.
APPLICATION OF DERIVATIVES
1. Verify Lagrange's Mean Value Theorem for the function f (x) = (x – 1) (x – 2) (x – 3)
in the interval [1, 4] (Ans. 3)
2. Verify Rolle's Theorem for the function
2,0x,xcosxsinxf
4c.Ans
3. A particle moves along the curve 6y = x3 + 2. Find the points on the curve at
which y co-ordinate is changing 8 times as fast as the x-co-ordinate.
Ans. (4, 11) &
331
,4
4. Find the intervals in which the function f (x) = x3 – 12x2 + 36x + 17 is (a) increasing
(b) decreasing Ans. (Increasing in (–, 2) U (6, ) decreasing in (2, 6)
5. Find the intervals in which the function f given by f (x) = sin x – cos x
2x0 (i) is increasing (ii) is decreasing
(Ans. Increasing when43
x0
or
2x47
Decreasing when47
x43
)
6. Find the intervals in which the function f (x) = 7 + 12x – 3x2 – 2x3 is increasing or
decreasing (Ans. (i) –2 x 1 & x < –2 or x > –1)
7. At what points on the curve x2 + y2 – 2x – 4y + 1 = 0, is the tangent parallel to
y-axis ? (Ans. (3, 2) & (–1, 2)
8. Prove that the curves x = y2 & xy = k cut at right angles if 8k2 = 1.
9. Find the Co-ordinates of the points on the curve y = 2x3 – 6x + 3 where the
tangents are || to x-axis. (Ans. (1, –1) & (–1, 7))
10. Find the equation of the tangent & normal to the curve.
x = 1 – cos , y = – sin at4
04
yx12normalofEquation
1224
yx12genttanofEquation.Ans
(9) XII/Maths.
11. Using differentials, find the approximate value of
(i) 037.0 (Ans. 0.1925)
(ii) 48.0 (Ans. 0.693)
12. Find the approximate value of f (2.01), when f (x) = 4x2 + 5x + 2 (Ans. 28.21)
13. If y = x4 – 10 and if x changes from 2 to 1.97, using differential, find the approxi-
mate change in y. (Ans. – 0.96)
14. Find the points of local maxima or local minima for the function f (x) = sin x – cos x,
0 < x < 2. (Ans. max value =43
xat2
, min value =47
xat2
15. Show that the rectangle of max. area that can be inscribed in a circle of radius r is
a square of side 2 r..
16. Find the point on the curve y2 = 4x which is nearest to the point (2, –8). (Ans. (4, –y)
17. Two sides of a triangle have lengths 'a' & 'b' and the angle between them is .What value of will maximize the area of the triangle ? Find the max. area of the
triangle also. (Ans. = /2, max area = ½ ab
18. A wire of length 25 m is to be cut into two pieces. One of the two pieces is to be
made into a square and the other into a circle. What should be the lengths of the
two pieces so that the combined area of the square & the circle is minimum ?
m425
&m4100
.Ans(
)
19. An open 60x, with a square base is to be made out of a given quantity of metal
sheet of area c2. Show that the max volume is36
c3
.
20. A window is in the form of rectangle surmounted by a Semi circle. If the total
perimeter of the window is 30 m, find the dimensions of the window so that max.
light in admitted.
m
430
.Ans
21. Show that the height of the cylinder of max. volume that can be inscribed in a
sphere of radius R is3
R2.
(10) XII/Maths.
INTEGRATION
Evaluate :
1. dxx3sinx2sinxsin
2. dxx3cosx2cos.xcos
3. dxxsin 4
4. dxcos 4
5. dxxtan4
6.
dxcosxcos
2cosx2cos
7. dx
xsinxsindx
8. xtan1dx
9. dxxlogx
10. dxxsec3
11. dxx1
xe2
x
12.
dxex2cos1x2sin2 x
13. dxxsinx 1
14. dxxtanx 1
15. dxxtanx 12
16.
dxx11x4
2
17.
dxx11x4
2
18. 4x1dx
19. dxbxsineax
20. dxbxcoseax
21. dxxtan
22. dxxcot
23. dxxcotxtan
24. xsin45dx
25. 1xxxxdx
23
26. 1xxdxn
27. xsin2xsin1xdxcos
28. 1xdx3
29. 2xx1
dx
30. dx1x4x
1x22
31. 2x1xdx2
32. dxxx431x2 2
(11) XII/Maths.
INTEGRATION AS A LIMIT OF SUM
Evaluate following integrals as the limit of sums :
1. 5
0
dx1x
2. 3
2
2dxx
3. 2
0
2 dx3x
4. 4
1
dx2x3
5. 3
1
2dxx
6. 3
0
2 dx5x2
7. 2
0
x dxe
8. 3
1
2 dxx5x2
9. 3
1
3 dxx
10. 2
0
2 dx2xx
(12) XII/Maths.
DEFINITE INTEGRALS
1.
4
0
dxx3sin.x2sin
25
3.Ans
2. 2.Ansdxxcotxtan2
0
3.
31
tan32
.Ansxsin45
dx 12
0
4.
4.Ansdx
xcosxsinxsin2
05
5
5.
2
19.Ansdx|3x||2x||1x|
4
1
6.
2log8
.Ansdtan1log4
1
7.
12.Ans
xtan1
dx3
6
8.
22
0
log2
.Ansdxxsinlog
9.
22
0
log2
.Ansdxx2sinlogxsinlog2
10. 0.Ansdxxcosxsin1xcosxsin2
0
11.
ab2.Ans
xsinbxcosaxdx 2
02222
12.
4.Ansdx
xcos1xsinx 2
02
(13) XII/Maths.
AREA OF THE BOUNDED REGION
1. Find the area of the region bounded by the ellipse 19y
4x 22
. (Ans. 6 sq unit)
2. Find the area of the region included between the Parabolas y2 = 4ax & x2 = 4ay.
unitsq
3a16
.Ans2
3. Find the area of the region {(x, y) x2 y x}
unitsq
61
.Ans
4. Find the area of the region {(x, y) x2 + y2 1 x + y}
unitsq21
4.Ans
5. Find the area of the region enclosed between the two circles x2 + y2 = 1 and
(x – 1)2 + y2 = 1
unitsq23
32
.Ans
6. Find the area of the region {(x, y) : x2 y |x|}
unitsq
31
.Ans
7. Find the area enclosed by the Parabola x2 = 4y and the straight line x = 4y – 2
unitsq
89
.Ans
8. Find the area of the region enclosed between the circles x2 + y2 = 4 and
(x – 2)2 + y2 = 4
unitsq3238
.Ans
9. Find the area of the smaller region bounded by the ellipse 1by
ax
2
2
2
2
& the
line 1by
ax
unitsq122
ab.Ans
10. Using integration, find the area of the triangle whose vertices are (1, 0), (2, 2)
& (3, 1)
unitsq
23
.Ans
11. Using integration, find the area of ABC when A is (2, 3), B is (4, 7) & C is (6, 2)
(Ans. 9 sq unit)
12. Find the area of the region bounded by the lines x + 2y = 2, y – x = 1 & 2x + y – 7 = 0
(Ans. 6 sq unit)
(14) XII/Maths.
DIFFERENTIAL EQUATION
1. Verfiy that x1sinmey
is a solution of the differential equation
0ymdxdy
xdx
ydx1 2
2
22
2. F o r m t h e d i f f e r e n t i a l e q u a l c o r r e s p o n d i n g t o ( x – a )
2 + (y – b)2 = r2 by eliminating
a & b. (Ans. (1+y12)3 = r2 (y2)
2)
3. Solve the differential equation
dxdy
yadxdy
xy 2
4. Solve the differential equation (1 + e2x)dy + ex (1 + y2) dx = 0 Given y = 1, when x = 0
5. Solve the differential equation 0y1dxdy
x1 22 Given y = 1 when x = 0
6. Solve the differential equationdxdy
yxdxdy
xy
7. Solve the differential equation 0dyyx
1edxe1 yx
yx
8. Solve the differential equation dxyxdxydyx 22
9. Solve the differential equation dxyxdxydyx 22
10. Solve the differential equation x2 dy + (xy + y2) dx = 0 given that y = 1 when x = 1
11. Solve the differential equation (1 + y2)dx = (tan–1y – x)dy
12. Solve the differential equation ydxdy
y2x 2 given y = 1 when x = 2
13. Solve the differential equation xtanydxdy
x1 12
14. Solve the differential equation 22 yxy2dxdy
x
15. Solve the differential equation xlogxy2dxdy
x 2
16. Solve the differential equation xsinydxdy
xcos given that y = 2 when x = 0
(15) XII/Maths.
VECTORS & 3–DIMENSIONAL GEOMETRY
1. If ji3c&kib,k3j2ia
find the value of such that ca is to b.
34
.Ans
2. Find a unit vector in the direction of the sum of the vectors
k3ji2b&kjia
k2j2i
31
.Ans
3. Find the value of for which the vectors k8j4ib&k4j2i3a
are
parallel. (Ans. = 6)
4. If kjb&kjia
, find the vector c such that 3c.a&bca
k
32
j32
i35
c.Ans
5. If |b.a|find,25|ba|&13|b|,5|a|
(Ans. 60)
6. Find the area of the ||gm whose adjacent sides are determined by the vectors
kj7i2b&k3jia (Ans. 15 2 sq unit)
7. If |ba|find,12b.a&2|b|,10|a| (Ans. 16)
8. Show that the points (2, –1, 2), (4, 5, –6) & (3, 2, –2) are collinear.
9. If 0cba
Prove that accbba
10. Prove that cba2accbba
11. Find the foot of the r from the point (1, 2, 3) on the line23z
31y
12x
4
21
,23
.Ans
12. Find the shortest distance between the lines
k2ji2kji2r&kjikj2ir
unit
2
3.Ans
13. Find the shortest distance between the following lines
11z
61Y
71x
&1
7z25Y
13x
unit292.Ans
(16) XII/Maths.
14. Find the equation of the plane Passing through the points (1, 1, 0), (1, 2, 1) & (–2, 2, –1)
(Ans. –2x – 3y + 3z + 5 = 0)
15. Find the equation of the plane passing through the points (2, 1, –1) & (–1, 3, 4)
and r to the plane x – 2y + 2 = 0 (Ans. 10x + 5y + 4z – 21 = 0)
16. Find the equation of the plane passing through the points A (2, 3, –1), B (–2, 4, 5)
& C (0, 1, 2) in vector form. Also express it in Cartesian form.
17. The Cartesian equations of a line are 3x + 1 = 6y – 2 = 1 – z. Find the fixed point
through which it passes, its direction rations and also its vector equation.
6,1,2;1,31
,31
.Ans
k6ji2kj31
i31
r
18. Find the value of so that lines5
z61
5y3
x77&
23z
214y7
3x1
are at right angle.
1170
.Ans
19. Find the image of the point (1, 6, 3) in the line3
2z2
1y1x
. Also, write the
equation of the line Joining the given point and its image and find the length of
the segment joining the given point and its image.
132,y
3z66y
01x
,7,0,1.Ans
20. Find the angle between the planes 5k2ji.r&6kji2.r 3.Ans
21. Find the image of the point (3, –2, 1) in the plane 3x – y + 4z = 2 (Ans. 0, –1, –3)
22. Prove that the lines7
6z4
4y1
2x&
75z
53y
31x
are coplanar. Also
find the plane containing these two lines.
23. Find the equation of the plane passing through the intersection of the planes
5k4j3i2.r&6kji.r
and the point (1, 1, 1)
69k26j23i20.r.Ans
(17) XII/Maths.
LINEAR PROGRAMMING
1. Solve the following Linear Programming Problem graphically
Maximize z = 50 x + 15 y
Subject to 5x + y 100
x+ y 60
x, y 0 (Ans. 1250)
2. A diet is to contain at least 80 units of vitamin A and 100 units of minerals. Two
foods F1 & F2 are available. Food F1 costs Rs. 4 per unit and F2 costs Rs. 6 per
unit, one unit of food F1 contains 3 units of vitamin A and 4 units of minerals.
One unit of food F2 contains 6 units of vitamin A and 3 units of minerals. Formu-
late this as a linear programming problem and find graphically the minimum
cost for diet that consists of mixture of these foods & also meets the mineral
nutritional requirements. (Ans. Rs. 104)
3. One kind of cake requires 300 gm of flour and 15 gm of fat, another kind of cake
requires 150 gm of flour & 30 gm of fat. Find the max. number of cakes which
can be made from 7.5 kg of flour and 600 gm of fat, assuming that there is no
shortage of the other ingradients used in making the cakes. Make it as an LPP
and solve it graphically. (Ans. 20, 10)
4. There are two types of fertilisers 'A' and 'B' A' consists of 12% Nitrogen & 5%
phosphoric acid where as 'B' consists of 4% nitrogen and 5% phospheric acid.
After testing the soil conditions, farmers finds that he needs at least 12 kg of
nitrogen & 12 kg of phosphoric acid for his crops. It 'A' costs Rs. 10 per kg and 'B'
cost Rs. 8 per kg, then graphically determine how much of each type of fertiliser
should be used so that nutrient requirements are met at a minimum cost.
(Ans. A 0.3 kg, B : 0.21 kg)
5. Solved the following linear programming problem graphically
Maximize z = 60x + 15y Subject to constraints
x + y 50
3x + y 90
x, y 0
(Ans. x = 20, y = 30, z = 1650)
(18) XII/Maths.
6. A farmer mixes two brands P and Q of cattle feed. Brand P, costing Rs. 250 per
bag, contains 3 units of nutritional element A, 2.5 units of element B and 2 units
of element C whereas brand Q costing Rs. 200 per bag contains 1.5 units of
nutritional element A, 11.25 units of element B and 3 units of element C. The
minimum requirements of nutrients A, B and C are 18 units, 45 units and 24
units respectively. Determine the number of bags of each brand which should be
mixed in order to produce a mixture having a minimum cost per bag ? What is
the minimum cost of the mixture per bag ? (Ans. Rs. 1950 at (3, 6)
7. An aeroplane can carry a maximum of 200 passengers. A profit of Rs. 1000 is
made on each exclusive class ticket and a profit of Rs. 600 is made on each
economy class ticket. The airline reserves at least 20 seats for executive class.
However at least 4 times as many passengers prefer to travel by economy class
than by the executive class. Determine how many tickets of each type must be
sold in order to maximise the profit for the airline. What is the maximum profit ?
(Ans. Max profit Rs. 136000 at (40,160)
8. Two godowns A and B have grain capacity of 100 quintals and 50 qunitals re-
spectively. They supply to 3 ration shops D, E and F, whose requirements are 60,
50 and 40 quintals respectively. The cost of transportation per quintal from the
godowns to the shops are given in the following table :
How should the supplies be transported in order that the transportation cost in
minimum. What is the minimum cost ?
Transportation cost per quintal (in Rs.)
From/To A B
D 6 4
E 3 2
F 2.50 3
(Ans. : Minimum cost Rs. 510 at (10, 50))
(19) XII/Maths.
PROBABILITY
1. If A & B are two events such that 41
BAP&31
BP,21
AP Find
(i) P (A/B) (ii) P (B/A) (iii) B/AP (iv) B/AP
85
,41
,21
,43
.Ans
2. A problem in Mathematics is given to 3 students whose chances of solving it are
41
,31
,21
. What is the probability that te problem is solved ?
43
.Ans
3. Two persons A & B throw a die alternately till one of them gets a 'three' and wins
the game. Find their respectively probabilities of winning, if A begins.
115
,116
.Ans
4. Three persons A, B, C throw a die in succession till one gets a 'six'and wins the
game. Find their respective probabilities of winning, if A begins.
9125
&9130
,9136
.Ans
5. A husband and wife appear in an interview for two vacancies for the same post.
The probability of husband's selection is71
and that of wife's selection is51
.
What is the probability that
(i) both of them will be selected ?
351
.Ans
(ii) only one of them will be selected ?
72
.Ans
(iii) none of them will be selected ?
3524
.Ans
6. In a bolt factory, machines A, B and C manufacture respectively 25%, 35% and
40% of the total bolts of their output 5, 4 and 2 percent are respectively defective
bolts. A bold is drawn at random from the product. If the bolt drawn is found to
be defective, what is the probability that it is manufactured by the machine B ?
6928
.Ans
7. A Insurance company insured 2000 scooter drivers, 4000 car drivers and 6000
truck drivers. The probabilities of an accident involving a scooter driver, car driver
& a truck driver are 0.01, 0.03 and 0.15 respectively. One of the insured person
meet with an accident. What is the probability that he is a scooter driver ?
521
.Ans
(20) XII/Maths.
8. A card from a pack of 52 cards is lost. From the remaining cards of the pack, two
cards are drawn and are found to be hearts. Find the probability of missing card
to be a heart.
5011
.Ans
9. A man is known to speak truth 3 out of 4 times. He throws a die and reports that
it is a six. Find the probability that it is actually a six.
83
.Ans
10. There are three coins. One is two headed coin, another is a biased coin that
comes up heads 75% of the time and third is an unbiased coin. One of the three
coins is choosen at random and tossed, it shows heads, what is the probability
that it was the two headed coin ?
94
.Ans
11. Three urns A, B and C contain 6 red an 4 white ; 2 red and 6 white; and 1 red and
5 white balls respectively. An urn is chosen at random and a ball is drawn. If the
ball drawn is found to be red, find the probability that the ball was drawn from
urn A.
6136
.Ans
12. A random variable X has the following probability distribution :
X : 0 1 2 3 4 5 6 7
P (x) : 0 k 2k 2k 3k k2 2k2 7k2+k
Find each of the following :
(i) k (ii) P (x < 6) (iii) P (x 6) (iv) P (0< × <5)
54
,10019
,10081
,101
.Ans
13. Find the mean & variance of the number of tails in three tosses of a coin.
43var,5.1Mean