CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion
The mean of the numbers 5, 8, x, 12 and 2x is 11. What is the value of x?
The value of x is 10. The five numbers must add to 5 × 11 = 55. The sum is 25 + 3x, so 3x = 30 and x = 10. Substituting back gives 5, 8, 10, 12, 20, which total 55 and average 11.
- A10Correct
- B12
- C9
- D11
Explanation
Sum = 5 + 8 + x + 12 + 2x = 25 + 3x. Setting 25 + 3x = 5 × 11 = 55 gives 3x = 30, so x = 10. Check: 5 + 8 + 10 + 12 + 20 = 55, and 55/5 = 11. The option 12 results from dividing 55 − 19 incorrectly.
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