The highway speeds of 100 cars are summarized in the frequen

The highway speeds of 100 cars are summarized in the frequency distribution below. Find the mean speed. 30-39 4 40-49 19 50-59 50 60-69 15 70-79 12

Solution

C.I = CLASS INTERVAL , X = FREQUENCY

CI X   

30-39 04

40-49 19

50-59 50

60-69 15

70-79 12

FOR FINDING THE MEAN WE HAVE TO TAKE THE MEAN OF THE CLASS INTERVAL

CI MID X MID*X

30-39 34.5 4 138

40-49 44.5 19 845.5

50-59 54.5 50 2725

60-69 64.5 15 967.5

70-79 74.5 12 894

TOTAL 100 5570

MEAN = 5570/100 = 55.70