# St 101 Practice Exam

**Topics:**Normal distribution, Standard deviation, Arithmetic mean

**Pages:**10 (2758 words)

**Published:**April 27, 2012

Practice Problems Exam 1

Material covered: Chapters 1-7 in text.

Reiland

Important Note: While most of the questions on this sample exam are in a multiple choice format, the questions on the exam will for the most part be partial credit type questions where you must show some work to obtain full credit. 1. The heights of American men aged 18 to 24 can be described by a Normal model with mean 68 inches and standard deviation 2.5 inches. Half of all young men are shorter than a) 65.5 inches b) 68 inches c) 70.5 inches d) can't tell because the median height is not given Use the information in Problem 1 and the 68-95-99.7 rule to determine the percentage of young men that are taller than 6' 1". The grade point averages (GPA) of 7 randomly chosen students in a statistics class are 3.14 2.37 2.94 3.60 1.70 4.00 1.85 The mean GPA for these students is a) 2.8 b) 2.94 c) 3.6 d) none of the above

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Refer to the information given in the previous problem. If !(C C)# œ 4.51, what is the standard deviation?

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A standardized test designed to measure math anxiety has a mean of 100 and a standard deviation of 10 in the population of first year college students. Which of the following observations would you suspect is an outlier? a) 150 b) 100 c) 90 d) 125 e) none of the above Which of the following best describes a risk in using the range to measure spread of a data set? Choose one of the following: a) The range is not in the same unit of measurement as the observations themselves. b) The largest or smallest observation may be a mistake or an outlier. c) The range is complicated to compute, which may result in an error. d) The range might be negative so it doesn't make sense to use the range as a measure of spread.

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The distribution represented by the histogram below is: f| | |----- | | | |----- | | |----- | | | |---- | | | |----- | | | | | | |----- | | | | | | | |----- | | | | | | | | |----- | | | | | | | | | |----- | | | | | | | | | | |----- | --------------------------------------------------------------------------- X 0 1 2 3 4 5 6 7 8 9 10 Choose one of the following: a) skewed to the right. b) skewed to the left. c) symmetric. d) normal.

ST 101

8.

Practice Problems Exam 1

page 2

Twenty-seven applicants interested in working for the Food Stamp program took an examination designed to measure their aptitude for social work. The following test scores were obtained: 79, 93, 84, 86, 77, 63, 46, 97, 87, 88, 87, 92, 68, 72, 86, 98, 81, 70, 66, 98, 59, 76, 68, 91, 94, 85, 88. a. Find U" . b. Construct a boxplot for these observations. Do you observe any outliers? A manufacturer of television sets has found that for the sets he produces, the lengths of time until the first repair can be described by a normal distribution with a mean of 4.5 years and a standard deviation of 1.5 years. If the manufacturer sets the warrantee so that only 10.2% of the 1st repairs are covered by the warrantee, how long should the warrantee last?

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10. Suppose the amount of tar in cigarettes is described by a normal model with a mean of 3.5 mg and a standard deviation of 0.5 mg. a. What proportion of cigarettes have a tar content that exceeds 4.25 mg? b. In order to advertise as a low tar brand, a manufacturer must prove that their tar content is below the 25th percentile of the tar content distribution. Find the 25th percentile of the distribution of tar amounts. 11. Has the percentage of young girls drinking milk changed over time? The following table is consistent with the results from “Beverage Choices of Young Females: Changes and Impact on Nutrient Intakes” (Shanthy A. Bowman, Journal of the American Dietetic Association, 102(9), pp. 1234-1239): Nationwide Food Survey Years 1987-1988 1989-1991 1994-1996 354 502 366 226 335 366 580 837 732

Drinks Fluid Milk

a. 1. 2. 3. 4.

Total Yes 1222 No 927 Total 2149 Find the following: What percent of the young girls reported that they...

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