Question

The speeds in miles per hour of 30
cars were checked by radar. The data are as follows:
62 67 69 72 75 60 58 86 74 68
56 67 82 88 90 54 67 65 64 68
74 65 58 75 67 65 66 64 45 64
Find the upper and lower quartiles

Answer 1

Rewrite the list in ascending order, and then divide the list into four parts. That will tell you the quartile boundaries.
45 54 56 58 58 60 62
64 64 65 65 65 66 67 67
67 67 68 68 69 72 74 74
75 75 82 86 88 90

Q2 = 67 (divides into upper and lower halves)
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Q1 = 64 (median of lower half)
Q3 = 74 (median of upper half)