# The average of 8 numbers is 20 The average of first…

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### The average of 8 numbers is 20. The average of first two numbers is $$15\frac{1}{2}$$ and that of the next three is $$21\frac{1}{3}$$ . If the sixth number be less than the seventh and eighth numbers by 4 and 7 respectively, them the eighth number is :

1. A. 18
2. B. 22
3. C. 25
4. D. 27

$$Rightarrow 2 times frac{{31}}{2} + 3 times frac{{64}}{3} + x + x + 4 + x + 7$$        = 8 × 20
eqalign{ & Rightarrow 31 + 64 + 3x + 11 = 160 cr & Rightarrow 106 + 3x = 160 cr & Rightarrow 3x = 54 cr & Rightarrow x = 18 cr}