Questions from Statistics

Q: Wechsler IQ tests have a mean of 100 and a standard deviation

Wechsler IQ tests have a mean of 100 and a standard deviation of 15. Which is more unusual: an IQ above 110 or an IQ below 80?

Q: Distributions of gestation periods (lengths of pregnancy) for humans are

Distributions of gestation periods (lengths of pregnancy) for humans are roughly bell-shaped. The mean gestation period for humans is 272 days, and the standard deviation is 9 days for women who go in...

Q: Babies born weighing 2500 grams (about 5.5 pounds)

Babies born weighing 2500 grams (about 5.5 pounds) or less are called low-birthweight babies, and this condition sometimes indicates health problems for the infant. The mean birth weight for U.S.-born...

Q: Students who have accumulated fewer than 30 units are called Freshmen.

Students who have accumulated fewer than 30 units are called Freshmen. a. Create a new categorical variable, named Freshman, that classifies each student in Table 1A as a freshman (less than 30 units)...

Q: Babies born after 40 weeks gestation have a mean length of 52

Babies born after 40 weeks gestation have a mean length of 52.2 centimeters (about 20.6 inches). Babies born one month early have a mean length of 47.4 centimeters. Assume both standard deviations are...

Q: Assume that men’s heights have a distribution that is symmetric and unimodal

Assume that men’s heights have a distribution that is symmetric and unimodal, with a mean of 69 inches and a standard deviation of 3 inches. a. What men’s height corresponds to a z-score of 2.00? b. W...

Q: Assume that women’s heights have a distribution that is symmetric and unimodal

Assume that women’s heights have a distribution that is symmetric and unimodal, with a mean of 64 inches and a standard deviation of 2.5 inches. a. What women’s height corresponds with a z-score of -1...

Q: The histogram shows the number of runs scored by major league baseball

The histogram shows the number of runs scored by major league baseball teams for three seasons. The distribution is roughly unimodal and symmetric, with a mean of 687 and a standard deviation of 66 ru...

Q: Data on residential energy consumption per capita (measured in million BTU

Data on residential energy consumption per capita (measured in million BTU) had a mean of 70.8 and a standard deviation of 7.3 for the states east of the Mississippi River. Assume that the distributio...

Q: Name two measures of the variation of a distribution, and state

Name two measures of the variation of a distribution, and state the conditions under which each measure is preferred for measuring the variability of a single data set.