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The average of 8 numbers is 20. The average of first two numbers is
seventh and eighth numbers by 4 and 7 respectively, then the eighth number is :15 1 and that of the next three is 21 1 If the sixth number be less than the 2 3
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- 18
- 22
- 25
- 27
- 18
Correct Option: C
According to question ,
Sum of 8 numbers = 20 × 8 = 160
| Sum of the first two numbers = | × 2 = 31 | |
| 2 |
| Sum of next three numbers = | × 3 = 64 | |
| 3 |
Sum of the remaining three numbers = 160 – (31 + 64)
Sum of the remaining three numbers = 160 – 95 = 65
Let 6th number = p
∴ 7th number = p + 4,
8th number = p + 7
⇒ p + p + 4 + p + 7 = 65
⇒ 3p = 65 – 11
| ⇒ p = | = 18 | |
| 3 |
∴ Eighth number = p + 7 = 18 + 7 = 25
