If 2x + 1, x + 2, 2 and 5 are in proportion, then what is the mean proportion between 3.5(1 – x ) and 8(1 + x)?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e 5.25.
| Understanding/Application |
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2x + 1, x + 2, 2 and 5 are in proportion. So, (2x + 1)/(x + 2) = 2/5 10x + 5 = 2x + 4 8x = -1 x = -1/8 |
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Mean proportional between 3.5(1 - x) and 8(1 + x) Numbers = 3.5(1 + 1/8) and 8(1 + 1/8) = 31.5/8 and 7 Mean proportional = √(31.5/8 × 7) = √27.5625 = 5.25 |