AP Stats Chapter 8

The Gallup poll said that 39% of a random sample of 300 people make lunch their big meal of the day. The standard error of the sample proportion is approximately

• .488

• .032

• .0282

As students were leaving the cafeteria Dr. O flipped a coin and if it landed on heads he asked if the bought lunch that day. After all the lunches he found 200 of the 350 bought lunch. What condition was not met.

• sample size was not large enough

• large counts

• np and n(1-p) >=10

• the data was a random sample

In a report of 2000 survey children they said, "With a 98% confidence between 20% and 50% of all parents make their children eat breakfast. What does 98% confidence mean?

• we can be 98% confident that the method used to get the intervals always gives the correct answer

• 98% of all parents will make their kids eat breakfast

• The method used to find the interval when used over and over produces intervals which include the true proportion about 98% of the time

To estimate the amount of seniors who will go to college the administration need a random sample and they want a 96% confidence level and a margin of error of 5%. How big is the sample size

• 422

• 419

• 410

• 400

Which of the following has the highest probability?

• randomly selecting a value greater than 2 from a t-distribution with 30 degrees of freedom

• Randomly selecting a value less that 2 from a standard normal distribution

• randomly selecting a value greater than 2 from a t-distribution with 5 degrees of freedom

Mrs. Fryer polled 1000 adults and estimated with 90% confidence that the proportion of adults who have dessert after dinner is .75. Mrs. Heinz things that 90% confidence isn't enough and wants to do a 95% confidence. How would a margin of error for 95% compare with a ME for 90% if the same sample size was used?

• It would be smaller because a higher C means a higher ME

• It would be larger because a higher C means a higher ME

• It would be the same because the sample size is the same

• Won't be able to tell

You want to calculate a 94% confidence interval for a population mean with a sample of n = 20. What is the appropriate t*

• 1.88

• 2.000

• 1.99

• 1.80

5 year old boys heights are approximately normal. The mean height of a random sample of 37 5 year old boys is found to be 30 inches with a standard deviation of 3 inches. What is the standard error of x(bar)

• .49

• 1.32

• 5.77

• 1.96

For using a t-distribution, the shape of the graph can be ________ but can not have ___________

• normal, skew

• mod skew, long tails

• mod skew, outliers

Mr. Miller wants to find the sample needed to find with 95% confidence the mean amount of time a stat kid does hw. The population is app normal and the known standard deviation is 6 minutes. How large should the sample size be if he wants a margin of error of +- .5 minutes.

• 553

• 551

• 600

• 601