The mean height of 25 boys in a class is 150 cm , and the mean height of 35 girls in the same class is 145 cm . The combined mean height of 60 students in the class is `”_______”` (approximately).
A. 143 cm
B. 146 cm
C. 147 cm
D. 145 cm
A. 143 cm
B. 146 cm
C. 147 cm
D. 145 cm
Correct Answer – c
Given `n_(1) = 25 , n_(2) = 35`
`barx_(1) = 150` and `barx_(2) = 145`
Combined mean , `barx = (n_(1) barx_(1) + n_(2)barx_(2))/(n_(1) + n_(2))`
`barx = (25 xx 150 + 35 xx 145)/(25 + 35) = (3750 + 5075)/(60)`
`= (8825)/(60) = 147` (approximately ) .