Question

8.53
25. The mean weight of a group of 20 items is 25 and that of another group of n items is 34. The mean of
combined group of 20 +n items is found to be 32. The value of n is:
(b) 10
(d) 50
(a60
C 70
ean?
Measures of Central Tendency - Arithmetic Mean​

Answer 1

Given:

The correct option is "c"

Mean weight of 20 items=25

⇒  Sum of weight of 20 items/20  =25

⇒Sum of weight of 20 items=25×20=500kg

Given Mean weight of n items=34

Sum of weight of n items  /n =34

Sum of weight of n items=34n

Sum of weight of 20+n items/20+n=32

Sum of weight of 20 items + Sum of weight of n items/20+n=32

500+34n/20+n=32

500+34n=32(20+n)

500+34n=640+32n

500-640+34n-32nn=0

-140+2n=0

2n=140

n=70