Out of four numbers , the average of first three is 16 and that of the last…
2023
Out of four numbers , the average of first three is 16 and that of the last three is 19. If the last number is 13 , the first number is
- A.
4
- B.
6
- C.
8
- D.
10
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Correct answer: A
Answer: 4
Let the four numbers be a, b, c, d.
Average of the first three is 16, so a + b + c = 16 × 3 = 48.
Average of the last three is 19, so b + c + d = 19 × 3 = 57.
Subtract the first equation from the second to get d − a = 57 − 48 = 9.
Given d = 13, so a = 13 − 9 = 4.
Therefore the first number is 4.