Question

Find the mean of the data summarized in the given frequency distribution. The test scores of 40 students are summarized in the frequency distribution below. Find the mean score.50-59 1460-69 670-79 780-89 890-99 5a.)70.5 b.) 63.5 c.) 67.0 d.)74.5

Answer 1

70.5

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