CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion
The mean of a set of 5 numbers is 24. If each number is first multiplied by 3 and then 4 is subtracted from each result, what is the mean of the new set?
The new mean is 68. Multiplying every value by 3 multiplies the mean by 3, giving 72, and subtracting 4 from each value reduces the mean by 4, giving 68.
- A72
- B68Correct
- C76
- D20
Explanation
Mean is affected by change of origin and scale. New mean = 3 × 24 − 4 = 72 − 4 = 68. The option 72 ignores the subtraction, and 20 wrongly subtracts 4 without applying the multiplication properly.
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