Question

The mean weight of a group of 10 items is 28 and that of another group of n items is '35. The mean of combined
group
of 10+ n items is found to be 30. The value of n is:
(A) 2
(B)4
(C)10
(D) 12.
​

Answer 1

Answer:

n =4

10×28 =280

n × 35 = 35n

( 280 + 35n ) / (10 + n) = 30

280 + 35n = 300 + 30n

5n = 20

n = 4