If x is added to each of 14, 12, 34 and 30, the numbers so obtained, in this…
2019
If x is added to each of 14, 12, 34 and 30, the numbers so obtained, in this order, are in proportion. What is the value of √(12x + 9) ?
- A.
8
- B.
9
- C.
11
- D.
13
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Correct answer: B
Since 14 + x, 12 + x, 34 + x and 30 + x are in proportion, (14 + x)/(12 + x) = (34 + x)/(30 + x). Solving gives x = 6. Then sqrt(12x + 9) = sqrt(81) = 9.