PSYC - Unit 9 Module 22

In a normal distribution, ______ % of the distribution is above the mean, and ______ % of the distribution is below the mean.

50 ; 50

The average American male is 69 inches tall. Assuming that height is normally distributed with a standard deviation of 2.5 inches, we can conclude that 68% of males are between _______________ inches tall.

66.5 and 71.5 - If the mean is 69, and one standard deviation unit is equal to 2.5, then we can find the two heights between which 68% of males fall by subtracting 2.5 from 69 (= 66.5) and adding 2.5 to 69 (=71.5).

For a normal distribution, what percentage of scores fall within 1, 2, and 3 standard deviations, respectively?

68%, 95%, 99% - When data are normally distributed, 68% of the data fall within 1 standard deviation above and below the mean, 95% fall within 2 standard deviations above and below the mean, and 99% fall within 3 standard deviations above and below the mean.

The diagnosis of "mental retardation" is partly determined by an IQ score lower than ______, which is ______ standard deviation units below the average.

70; 2

The following table displays gas prices and the number of gas stations in a given town that offer gas at that price: Price Number of Stations $3.69 10 $3.79 13 $3.89 15 $3.99 12 $4.09 9 If gas prices were normally distributed, which gas price would most closely represent the center of the distribution?

$3.89 - A normal distribution is a bell-shaped frequency distribution, with the most frequent score at the center of the distribution. In this case, the most frequent gas price was $3.89; thus it would represent the center of the bell curve.

The average IQ is ______.

100

The classification of "giftedness" is partly determined by an IQ score of greater than _______, which is _______ standard deviations from the mean.

130; 2