Exam 5: Approximating With a Distribution

Use the following Heights of 10-year-old girls (5th graders) follow an approximately normal distribution with mean = 54.4 inches and standard deviation of = 2.7 inches. -What is the IQR of heights of 10-year-old girls? Note that you will need to find two endpoints of the distribution for your calculation. Report you answer with one decimal place.

Use the following The gas prices for a random sample of n = 10 gas stations in the state of Illinois on August 8, 2012 have a mean $3.975, with standard deviation $0.2266. -The standard error from the bootstrap distribution is SE = 0.069. Use the normal distribution to construct and interpret a 90% confidence interval for the mean gas price in Illinois (on August 8, 2012). Round all values to two decimal places.

Use the following Find the endpoint(s) on the normal density curve with the given property. -The area to the right of the endpoint on a N(100, 17) curve is about 0.05.

On November 15 - 18, 2012 Gallup conducted a survey of 1,015 randomly selected U.S. adults about "Black Friday" shopping. They asked the following question: "As you know, the Friday after Thanksgiving is one of the biggest shopping days of the year. Looking ahead, do you personally plan on shopping on the Friday after Thanksgiving, or not?" Of the 515 men who responded, 16% said "Yes." Of the 500 women who responded, 20% said "Yes."The standard error of the differences in proportions ( ) is about SE = 0.025. Use the normal distribution to test, at the 5% level, if the proportions of men and women who planned to shop on the Friday after Thanksgiving are significantly different. The sample size is large enough to use the normal distribution.

Use the following Final grades in Professor Albert's large calculus class are approximately normally distributed with a mean of 76 (%) and standard deviation of 8 (%). -What is the 25th percentile in this course? Report your answer with one decimal place.

Use the following Use the provided density function to choose the best estimate for the proportion of the population found in the specified region. -The percent of the population that is less than 20 is closest to

Use the following In an August 2012 Gallup survey of 1,012 randomly selected U.S. adults (age 18 and over), 53% said that they were dissatisfied with the quality of education students receive in kindergarten through grade 12. The bootstrap distribution (based on 5,000 samples) is provided. -Would it be appropriate to use the normal distribution to construct the confidence interval in this situation? Explain briefly.

Use the following Find the endpoint(s) on the normal density curve with the given property. -The symmetric middle area on a N(66, 6) curve is about 0.9.

Use the following Final grades in Professor Albert's large calculus class are approximately normally distributed with a mean of 76 (%) and standard deviation of 8 (%). -Draw a sketch of this normal distribution and label at least three points on the horizontal axis.

Use the following Robins are common birds in North America. Suppose that the wingspan of robins is approximately normal with mean 14 inches and standard deviation 0.7 inches. -The largest 20% of robins have wingspans longer than what value? Report your answer with two decimal places.

Use the following Find the endpoint(s) on a N(0, 1) density with the given property. -The area between $\pm z$ is about 0.99

Use the following Select the answer closest to the specified areas for a N(0, 1) density. -The area to the left of z = -1.52

Use the following A student suspects that the length of songs currently on his iPod are approximately normally distributed with a mean of 257 seconds and standard deviation 62 seconds. -The shortest 10% of songs are shorter than what length? Report your answer with one decimal place.

Use the following A student suspects that the length of songs currently on his iPod are approximately normally distributed with a mean of 257 seconds and standard deviation 62 seconds. -The longest 25% of songs are longer than what length? Report your answer with one decimal place.