Answer:
70.5
Step-by-step explanation:
Class interval frequency
50-59 14
60-69 6
70-79 7
80-89 8
90-99 5
Mean for frequency distribution=sumfx/sumf
where f is frequency and x is a midpoint.
midpoints for above five classes can be calculated as
(50+59)/2, (60+69)/2, (70+79)/2, (80+89)/2 and (90+99)/2.
The calculated midpoints(x) are
54.5,64.5,74.5,84.5 and 94.5.
Mean=xbar=14*54.5+6*64.5+7*74.5+8*84.5+5*94.5/14+6+7+8+5
Mean=xbar=763+387+521.5+676+472/40=2819.5/40=70.4875
Mean=xbar=70.5
