CA Foundation · Quantitative Aptitude · Sequence and Series
Three numbers are in GP with common ratio 2. If the middle number is 10, what is the sum of the three numbers?
The sum is 35. The middle term is 10 and the ratio is 2, so the terms are 5, 10 and 20. Adding them gives 35.
- A35Correct
- B30
- C25
- D40
Explanation
With the middle term 10 and r = 2, the first term is 10/2 = 5 and the third is 10 × 2 = 20. The sum is 5 + 10 + 20 = 35. The value 30 results from forgetting to include the first term correctly, for example 10 + 20.
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