What is a Sampling Distribution?

At a particular college, 78% of all students are receiving some kind of financial aid.The school newspaper selects a random sample of 100 students and 72% of the respondents say they are receiving some sort of financial aid. Which of the following is true?

•  78% is a population and 72% is a sample.
• 72% is a population and 78% is a sample
• 78% is a parameter and 72% is a statistic
• 72% is a parameter and 78% is a statistic

Increasing the sample size of an opinion poll will reduce the

• bias of the estimates made from the data collected in the poll.
• variability of the estimates made from the data collected in the poll.
• variability of opinions in the sample.
• variability of opinions in the population.

A statistic is an unbiased estimator of a parameter when

• the statistic is calculated from a random sample.
• in many samples, the values of the statistic are very close to the value of the parameter.
•  in a single sample, the value of the statistic is equal to the value of the parameter
• in many samples, the values of the statistic are centered at the value of the parameter.

A child is 40 inches tall, which places her at the 90th percentile of all children of similar age. The heights for children of this age form an approximately Normal distribution with a mean of 38 inches. Based on this information, what is the standard deviation of the heights of all children of this age? (AP1.2) 

• 0.20 inches
• 0.31 inches
• 1.21 inches
• 1.56 inches