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, then the eight number is-

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

Answer: Option C

Here is complete explanation of The average of 8 numbers is 20 The average of first….

Solution(By ExamCraze Team)

Let the eight number be x
Then, sixth number = (x - 7)
Seventh number = (x - 7) + 4 = (x - 3)
So,
$$ Leftrightarrow left( {2 times 15frac{1}{2}} right) + left( {3 times 21frac{1}{2}} right)$$     $$ + left( {x - 7} right)$$   $$ + left( {x - 3} right)$$   $$ + ,x = 8 times 20$$
$$eqalign{ & Leftrightarrow 31 + 64 + left( {3x - 10} right) = 160 cr & Leftrightarrow 3x = 75 cr & Leftrightarrow x = 25 cr} $$

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