Multiple choice

Present ages of Ram and his father are in the ratio 2 : 3. After 5 years, ratio of ages of Ram's father and his mother will be 13 : 12. If the present age of his mother is 55 years, then what will be the age of Ram (in years) 7 years from now?

  1. 43

  2. 47

  3. 42

  4. 45
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The coefficient of variation (CV) is (Standard Deviation / Mean) * 100. Mean = Assumed Mean + (Sum of deviations / N) = 4 + (-11/100) = 3.89. Variance = (Sum of squares of deviations / N) - (Sum of deviations / N)^2 = (257/100) - (-11/100)^2 = 2.57 - 0.0121 = 2.5579. SD = sqrt(2.5579) = 1.599. CV = (1.599 / 3.89) * 100 = 41.11%.

AI explanation

Let the present ages of Ram and his father be 2x and 3x. After 5 years, the father's age will be 3x + 5, which corresponds to 13 units in the 13:12 ratio, while the mother is 55 + 5 = 60 years old (12 units). Solving 3x + 5 = 60 / 12 * 13 gives 3x + 5 = 65, so 3x = 60 and x = 20. Ram's present age is 2(20) = 40, making his age 7 years from now equal to 47.

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