Math CentralQuandaries & Queries



Please help me solve this question.

Thank you so much.

The cumulative frequency table below shows the length of time that 30 students spent text messaging on a weekend.

Minutes Used Cumulative Frequency
31-40 2
31-50 5
31-60 10
31-70 19
31-80 30

Which 10-minute interval contains the first quartile?

(1) 31–40

(2) 41–50

(3) 51–60

(4) 61–70


This is worded strangely. I think the question should be "Which 10-minute interval contains the boundary between the first quartile and the second quartile? "

There are 30 observations in total so the boundary between the first and second quartile is at 30/4 = 7.5. In which 10 minute interval would you find 7.5?


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