Oppsssssssssss...........
I'm stupid. Class width, c, will be 10.
For the set of data given below find or estimate, as appropriate, the quartiles.
Class| 1-9 | 10-19 | 20-29 | 30-39 | 40-49 | 50-59 | 60-69
Frequency| 3 | 6 | 12 | 18 | 10 | 4 | 2
Here is my work
Cumulative frequency| 3 | 9 | 21 | 39 | 49 | 53 | 55
Since n=55
So: Q₁ = b + {(¼ n – f)/fc} * c
= 19.5 + {(1/4 (55) – 9)/12} * 9 = 23.06
And Q₃ = 39.5 +{( ¾(55) – 39)/10} * 9 = 41.53
So my answers are Q₁ = 23.06 & Q₃ = 41.53
For this question, is it necessary to work for Q2? So far I know Q2 is median.
There is another problem; my answers are not accurate as per my book’s answer. It says 23.46 & 41.75. So where is the problem? Please help me.