Chapter 2: Q 38. (page 109)
If every observation in a data set is multiplied by , the only one of the following that is not multiplied by is
(a) the mean. (d) the standard deviation.
(b) the median. (e) the variance.
(c) the IQR.
The correct option is (e).
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R2.4 Aussie, Aussie, Aussie A group of Australian students were asked to estimate the width of their classroom in feet. Use the dot plot and summary statistics below to answer the following questions.
(a) Suppose we converted each student's guess from feet to meters . How would the shape of the distribution be affected? Find the mean, median, standard deviation, and IQR for the transformed data.
(b) The actual width of the room was feet. Suppose we calculated the error in each student's guess as follows: guess . Find the mean and standard deviation of the errors. How good were the students' guesses? Justify your answer.
Approximately locate the median (equal-areas point) and the mean (balance point) on a density curve.
A Normal curve Estimate the mean and standard deviation of the Normal density curve in the figure below:
T2.4. The figure shows a cumulative relative frequency graph of the number of ounces of alcohol consumed per week in a sample of adults. About what percent of these adults consume between and ounces per week?
(a)(b)(c)(d)(e)
Questions T2.9 and T2.10 refer to the following setting. Until the scale was changed in , SAT scores were based on a scale set many years ago. For Math scores, the mean under the old scale in the was and the standard deviation was . In , the mean was and the standard deviation was .
T2.10. Jane took the SAT in and scored . Her sister Colleen took the SAT in and scored . Who did better on the exam, and how can you tell?
(a) Colleen-she scored points higher than Jane.
(b) Colleen-her standardized score is higher than Jane's.
(c) Jane-her standardized score is higher than Colleen's.
(d) Jane-the standard deviation was bigger in
(e) The two sisters did equally well-their -scores are the same.
Growth charts We used an online growth chart to find percentiles for the height and weight of a -year-old girl who is inches tall and weighs pounds. According to the chart, this girl is at the percentile for weight and the percentile for height. Explain what these values mean in plain English.
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