Question

question 1:

The following data give the time (in minutes) that each of 20 students waited in line at their bookstore to pay for their textbooks in the beginning of Spring 2012 semester.

14	35	23	23	12
46	41	51	22	37
22	34	14	46	32
20	41	36	27	25

Construct a ranked stem-and-leaf display for the data.

Question 2:

Following are the temperatures (in   ∘F) observed during eight wintry days in a midwestern city (sample):

                            23⁢    17⁢    6⁢    −7⁢    −2⁢    11⁢    16⁢    12

Find the range, variance, and standard deviation.



Round your answers to two decimal places, where appropriate.

Range = Enter you answer; Range   ∘F

Variance = Enter you answer; Variance

Standard deviation = Enter you answer; Standard deviation   

Question 3:

A sample of 3000 observations has a mean of 86 and a standard deviation of 10. The distribution is bell-shaped. Using the empirical rule, find what percentage of the observations fall in the intervals x¯±1s, x¯±2s, and x¯±3s.

Enter the exact answers.


Approximately Enter you answer; 1s % of the observations fall in the interval x¯±1s.

Approximately Enter you answer; 2s % of the observations fall in the interval x¯±2s.

Answer 1

1)

Stem	Leaf
1	2 4 4
2	0 2 2 3 3 5 7
3	2 4 5 6 7
4	1 1 6 6
5	1

2)

Range = 30

Variance = 100.86

Standard deviation = 10.04

3)

Approximately Enter you answer; 1s % of the observations fall in the interval x¯±1s.

(76,96)

Approximately Enter you answer; 2s % of the observations fall in the interval x¯±2s.

(66,106)

Approximately Enter you answer; 3s % of the observations fall in the interval x¯±3s.

(56,116)

approximately 68% of observations lies within  x¯±1s.

approximately 95% fall within x¯±2s.

approximately 99.7% falls within x¯±3s.