Question

The following frequency table summarizes the number of hours worked by a sample of 120 students in the same week.

Hours worked by students
Class (hours)	Frequency
(0, 10]	10
(10, 20]	60
(20, 30]	40
30 or more	10
Total	120

A) How many students worked more than 10 hours but less than or equal to 30 hours?

B) What is the relative frequency of students who worked more than 10 hours but less than or equal to 20 hours?

C) What is the cumulative frequency of students who worked less than or equal to 30 hours?

D) What are the units of measure for this sample of data?

Answer 1

a)

100(60+40)  students worked more than 10 hours but less than or equal to 30 hours

.....

b)

class interval	frequency	relative frequency=fi/N
(0-10]	10	0.083
(10-20]	60	0.500
(20-30]	40	0.333
(30-40]	10	0.083

relative frequency of students who worked more than 10 hours but less than or equal to 20 hours = 0.5

...........

c)

class interval	frequency	relative frequency=fi/N	cumulative frequency
(0-10]	10	0.083	10
(10-20]	60	0.500	70
(20-30]	40	0.333	110
(30-40]	10	0.083	120

cumulative frequency of students who worked less than or equal to 30 hour =110

..........

D)

Hours worked by students

.............

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