Quiz 5

It is known that the mean weight of the population of newborn infants is 7.4 pounds with a standard deviation of 1.1 pounds. What is the weight (in pounds) of a newborn infant with a z score of +.67?

8.14 pounds

In a normal distribution, what is the percentile associated with a z score of +1.0?

84th

Assume that IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What is the z score for a person who has an IQ of 85?

-1.0

Roughly, to what percentile does a z score of -2.0 correspond?

2nd

In a normal distribution, 39.435% of scores fall between the mean and a z score of 1.25. What percent of scores fall between the mean and a z score of -1.25?

39.435%

According to the z table, what percentage of scores fall between the mean and a z of -1.96?

47.5%

In a normal distribution, ________ percent of the scores fall below the mean

50

In a normal distribution of scores, what is the percentile for someone who scores at the mean?

50th

In a normal distribution, approximately what percentage of scores fall between the z scores of -1.00 and + 1.00?

68%

There are several defining characteristics of the normal curve. They include:

unimodal, symmetrical, mesokurtic

In 2015, the mean SAT critical reading score for college-bound seniors was 495, with a standard deviation of 116. What is the z score for a person who scored 720?

1.94

In a normal distribution, what proportion of scores fall above a a z score of +1.0?

.15866

In a normal distribution, what proportion of scores fall between the mean and a a z score of +1.0?

.34134

In a normal distribution, what proportion of scores fall below a a z score of +1.0?

.84134

In a normal distribution, what proportion of scores fall between z scores of +1.96 and -1.96?

.95

In a normal distribution of scores, what is the z score for someone who scores at the mean?

0

It is known that the mean weight of the population of newborn infants is 7.4 pounds with a standard deviation of 1.1 pounds. Your sister just had a baby girl, Carlotta, who weighed in at 6.8 pounds. Calculate a z score for Carlotta's weight. What does this z score tell you about how Carlotta's weight compares with the weight of other newborn infants?

Carlotta's z score is -.55. This indicates that she weighs 0.55 standard deviations less than the average weight of the population of newborns.

Assume that IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Approximately what percent of the population have IQ scores between 100 and 130?

about 48%

Assume that IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Approximately what percent of the population have IQ scores between 85 and 115?

about 68%