CA Foundation · Quantitative Aptitude · Sequence and Series
The arithmetic mean of two positive numbers is 25 and their geometric mean is 24. What is their harmonic mean?
The harmonic mean is 23.04. For two positive numbers the geometric mean is the square root of the product of AM and HM, so HM equals GM squared divided by AM, which is 576 divided by 25, giving 23.04.
- A24.50
- B23.04Correct
- C24.00
- D25.00
Explanation
For two positive numbers, AM × HM = GM². So HM = GM²/AM = 576/25 = 23.04. The option 24.50 would come from wrongly averaging AM and GM, which is not a valid relation.
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