Question

criteek is a website where fans of horror films go to write movie reviews. on the websites home page there is a display of the number of movies reviewed by a selection of the sites top critics. the histogram below summarizes the data. use the histogram to answer each of the questions.
frequency
(number of critics)
10
9
8
7
6
5
4
3
2
1
0
7 to 14
15 to 22
23 to 30
31 to 38
number of movie reviews
(a) what is the class width?

(b) how many critics have from 31 to 38 movie reviews?

(c) how many critics have 30 or fewer movie reviews?

Explanation:

Step1: Find class width

Subtract lower bound of a class from next class's lower bound. For class 7 - 14 and 15 - 22: \(15 - 7 = 8\). Check others: \(23 - 15 = 8\), \(31 - 23 = 8\) (note: 23 to 30 and 31 to 38, but 30 + 1 = 31, so width is \(15 - 7 = 8\)).

Step2: Critics with 31 - 38 reviews

Look at histogram bar for 31 - 38. The height (frequency) is 6.

Step3: Critics with 30 or fewer reviews

Sum frequencies of 7 - 14, 15 - 22, 23 - 30. Frequencies: 2 (7 - 14), 7 (15 - 22), 5 (23 - 30). Sum: \(2 + 7 + 5 = 14\).

Answer:

(a) 8
(b) 6
(c) 14