STAT 100 Midterm: STAT100 ALL-SECTIONS SPRING1997 0000 MID EXAM

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turquoisegnu128

15 Feb 2019

School

University of Maryland

Department

Statistics and Probability

Course

STAT 100

Professor

All

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Document Summary

You may use calculators, but not books or notes. Di erent parts of a problem have equal weight unless otherwise indicated. Do not spend too much time on any one problem. Put a box around the nal answer to a question: (a) (15 pts. ) For the data 2, 5, 5, 2, 3 , calculate the sample mean, the sample standard deviation, and the median . (b) (5 pts. ) Suppose that data x1, x2, . xn has sample mean equal to 6. What is the sample mean of the data x1 + 3, x2 + 3, . xn + 3 : let the sample space s = {e1, e2, e3, e4, e5, e6}. Suppose p (e1) = p (e2) = . 2 and. P (e3) = p (e4) = . 05, and suppose e5 and e6 are equally likely. Why or why not: from a group of 25 cities, 4 will be randomly selected for a new pollution study.

Related Questions

1. In its standardized form, the normal distribution

(a) has a mean of 0 and a standard deviation of 1.

(b) has a mean of 1 and a variance of 0.

(d) cannot be used to approximate discrete probability distributions.

2. For some positive value of Z, the probability that a standard normal variable is between 0 and Z is 0.3770.

The value of Z is

(a) 0.18

(b) 0.81

(d) 1.47

3. For some value of z, the probability that a standard normal variable is below z is 0.2090. The value of Z is

(a) -0.81

(b) -0.31

(d) 1.96

4. For some positive value of X, the probability that a standard normal variable is between 0 and +2x is 0.1255.

The value of X is

(a) 0.99

(b) 0.40

(d) 0.16

5. If we know that the length of time it takes a college student to find a parking spot in the library parking lot follows a normal distribution with a mean of 35. minutes and a standard deviation of minute, find the probability that a randomly selected college student will find a parking spot in the library parking lot in less than 3 minutes.

(a) 0.3551

(b) 0.3085

(d) 0.1915

corallouse410

A reading comprehension test out of 90 points is given to a Grade 5 class of 30 students. Their scores are randomly listed below. 77 43 60 28 59 60 63 59 45 79 38 51 79 54 62 71 51 43 63 59 54 54 60 56 51 71 34 62 28 62 Part 1. (21 points) a. Prepare a frequency distribution table of the raw scores* grouped according to frequency (f). Also show the cf and the c% columns. For c% report up to 2 decimal places. Don’t round up. (*Hint: show only the scores in the data set.) (10 pts) b. Draw a bar graph of this f-distribution table. Be sure to label the axes. (4 pts) c. Make a stem and leaf display of the scores. Be sure to label the two columns of the display and arrange the leaves in ascending order. (4 pts) d. Find the percentile rank of X = 50. Use the f-distribution table with scores grouped according to class intervals, i = 5, in Part 2a below. (Hint: use the formula in the course Study Guide.) (3 pts) Part 2. (21 points) a. Prepare a f-distribution table with the scores grouped according to class intervals, i = 5. Show the f, cf, and c% columns. For c% report up to 2 decimal places. Don’t round up. (10 pts) b. Draw a histogram of this f-distribution table. (4 pts) c. Draw a polygon of this f-distribution table. (4 pts) d. Find the 20th percentile in this f-distribution table. (Hint: use the formula in the Course Study Guide.) (3 pts)

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STAT 100 Midterm: STAT100 ALL-SECTIONS SPRING1997 0000 MID EXAM

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