Answer:
Lower quartile= 4.75
Middle quartile= 9.5
Upper quartile= 14.25
Explanation:
The given date set is 24, 43, 65, 12, 31, 78, 43, 24, 25, 18, 29, 53, 18, 23, 20, 43, 53, 25
On counting them we notice that it's number of element is 18
So N = 18
Arranging them in ascending order gives
12,18,18,20,23,24,24,25,25,29,31,43,43,43,53,53,65,78
Lower quartile= (N+1)*1/4
Lower quartile= (18+1)/4
Lower quartile= 19/4
Lower quartile= 4.75
Middle quartile= (N+1)*2/4
Middle quartile= (18+1)*2/4
Middle quartile= (19)*2/4
Middle quartile= 9.5
Upper quartile= (N+1)*3/4
Upper quartile= (18+1)*3/4
Upper quartile= (19)*3/4
Upper quartile= 14.25
Inter quartile range = upper quartile- minutes lower quartile
= 14.25-4.75
= 9.5