7.3 and 7.4Extra Practice

7.3-7.4 Quiz: TOMORROW

THIS REVIEW IS

ON MY TEACHER

WEB PAGE!!!

Section 7.3

• Find the mean, median, and mode of the data set

1. 12, 15, 17, 11, 8, 14, 7, 14x = 12.25, Median = 13, Mode = 14

2. 0.3, 8.9, 7.6, 3.7, 1.5, 4.2, 7.6, 8.1x = 5.2375, Median = 5.9, Mode = 7.6

Section 7.3

• Find the range and standard deviation of the data set.

1. 1.25, 3.69, 5.67, 4.89, 0.12, 4.35, 2.78Range = 5.55, Standard Deviation = about 1.8

2. 515, 720, 635, 895, 585, 690, 770, 840Range = 380, Standard Deviation = about 119.6

Standard Deviationxi – x ( xi – x )2

Sum:

sum

n

Section 7.4

• A normal distribution has a mean x and standard deviation σ. Find the indicated probability for a randomly selected x-value from the distribution.

1. P(x < x + 2σ)97.5%

2. P(x > x – σ)84%

3. P( x - 3σ < x < x +σ)83.85%

Section 7.4

• Give the percent of the area under the normal curve represented by the shaded region.

2.5% 50%

Section 7.4• A normal distribution has a mean of 63.7 and a

standard deviation of 2.9. Find the probability that a randomly selected x-value from the distribution is in the given interval.

1. Between 57.9 and 66.681.5%

2. At most 69.597.5%

Section 7.4• A normal distribution has a mean of 496 and a

standard deviation of 109. Use the standard normal table on p. 296 to find the indicated probability for a randomly selected x-value from the distribution.

1. P(x < 630).8849 88.49%

2. P(x < 270).0179 1.79%