. The mean of 7 numbers is 10. If the mean of first 4 numbers is 8 and that of last 4 numbers is 16 then the fourth number is:


A. 20 B. 26 C. 30 D. 36

Best Answer

Answer ||| B

Solution |||

 

Given – The mean of 7 numbers is 10. The mean of first 4 numbers is 8 and that of last 4 numbers is 16.

To find – The fourth number

Mean of 1st seven numbers = 10

Sum of 1st seven numbers = 10 x 7 = 70

Mean of 1st four numbers = 8

Sum of 1st four numbers = 8 x 4 = 32

Mean of last four numbers = 16

Sum of last four numbers = 16 x 4 = 64

The fourth number

= (32 + 64) – 70

= 26

Hence, (B) is the answer

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