Chapter 2 Additional Review

Scores on the Wechsler Adult Intelligence Scale (a standard IQ test) for the 20 to 34 age group are approximately Normally distributed with µ = 110 and σ = 25.   1. What score would represent the 50th percentile?

2. Approximately what percent of the scores fall in the range from 70 to 130? Scores on the Wechsler Adult Intelligence Scale (a standard IQ test) for the 20 to 34 age group are approximately Normally distributed with µ = 110 and σ = 25.

Scores on the Wechsler Adult Intelligence Scale (a standard IQ test) for the 20 to 34 age group are approximately Normally distributed with µ = 110 and σ = 25. 3. A score in what range would represent the top 16% of the scores?

Runner’s World reports that the times of the finishers in the New York City 10-km run are normally distributed with a mean of 61 minutes and a standard deviation of 9 minutes.   4. Find the proportion of runners who take more than 70 minutes to finish.

Runner’s World reports that the times of the finishers in the New York City 10-km run are normally distributed with a mean of 61 minutes and a standard deviation of 9 minutes. 5. Find the proportion of runners who finish in less than 43 minutes.

Jill scores 680 on the mathematics part of the SAT Jill scores 680 on the mathematics part of the SAT. The distribution of SAT scores in a reference population is normally distributed with mean 500 and standard deviation 100. Jack takes the ACT mathematics test and scores 27. ACT scores are normally distributed with mean 18 and standard deviation 6.   6. a) Find the standardized scores for both students. b) who has the higher score, and why?

The Graduate Record Examinations are widely used to help predict the performance of applicants to graduate schools. The range of possible scores on a GRE is 200 to 900. The psychology department finds that the scores of its applicants on the quantitative GRE are approximately normal with mean 544 and standard deviation 103. 7 . What minimum score would a student need in order to score in the top 10% of those taking the test?

Brent is 74 inches tall and is a member of the school’s basketball team. The average height of the team is 76 inches. 8. If Brent is only taller than 20% of his teammates, what is the standard deviation of the team?

. Ninety-eight women and 225 men participated in a five kilometer road race. Here is the summary statistics from Minitab on their times in the race. 9. Suppose the timers of the race discovered that they accidently started the clock 15 seconds before the race actually started, so that each racer’s finish time should be 15 seconds less. What would be the new mean, median, standard deviation, and interquartile range of the adjusted data?

Mrs. Navard's statistics class has just completed an activity called “Where Do I Stand?”(they each measured their heights and recorded them in inches). The figure below shows a dot plot of the class’s height distribution, along with summary statistics from computer output.   10 a) Lynette, a student in the class, is 65 inches tall. Find and interpret her percentile and z-score. 10 b) Suppose that you convert the class’s heights from inches to centimeters (1 inch = 2.54 cm). Describe the effect this will have on the shape, center, and spread of the distribution.