From the test scores given:
42 45 50 57 60 63 66 70 73 78 85 87 90 94 95
splitting the values into 3 sets:
(42 45 50 57 60 )(63 66 70 73 78)( 85 87 90 94 95)
from the first set we select the median:
42 45 50 57 60
the median is 50
thus the first quartile will be 50
