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# Help with S1 question (Histograms)? Watch

1. In a particular week, a dentist treats 100 patients. The length of time, to the nearest minute , for each patient's treatment is summarised below.

Time(minutes): 4 - 7
Number of patients: 12

Time(minutes): 8
Number of patients: 20

Time(minutes): 9 - 10
Number of patients: 18

Time(minutes): 11
Number of patients: 22

Time(minutes): 12-16
Number of patients: 15

Time(minutes): 17-20
Number of patients: 13

Draw a histogram to illustrate these data.

The only bit which I don't understand is where the class width is 0 i.e. in the 8th and 11th minute. What's the frequency density for these 2?
2. for 8 the width is 1, from 7.5 to 8.5
3. What did you think the width was for 4-7?
4. (Original post by TenOfThem)
What did you think the width was for 4-7?
3 ain't it? So the frequency density is 4 since 12/3 = 4.
5. (Original post by Dr.Pwepper)
3 ain't it? So the frequency density is 4 since 12/3 = 4.
No

the width is 7.5 - 3.5 = 4

So the density is 3
6. (Original post by TenOfThem)
No

the width is 7.5 - 3.5 = 4

So the density is 3
Ah yes, I forgot about the upper and lower bound.

Thanks!

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Updated: February 19, 2012
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