Question

the mean of first 8 observation is 18 and last 8 observation is 20 if the mean of all 15 observation is 19 and find 8th observation

Answer 1

Heya mate......

The mean of first 8 observation = 18

So, Sum of first 8 observation = 8

> 18 = 144

And, the mean of last 8 observation = 20

So, sum of last 8 observation = 8

> 20 =160

Sum of 16 observation = 144 +160 = 304

Sum of 15 observation = (15

> 19 =285

Eighth observation = (sum of 16 observation) – (sum of 15 observation)

   = (304) – (285) = 19

Hence, 8th observation is 19.

@skb❤