The sum of deviations of n numbers from 10 and 20 are a, b respectively. If \frac{b}{a}=-4; then what is the mean of these n numbers?
- A. 12 ✓
- B. 14
- C. 16
- D. 18
Correct Answer: A. 12
Explanation
Let sum of numbers be S. Deviations: a = S - 10n and b = S - 20n. Given b = -4a, we have S - 20n = -4(S - 10n) \implies S - 20n = -4S + 40n \implies 5S = 60n \implies \frac{S}{n} = 12. The mean is 12.
Related questions on Statistics & Probability
- On an average, how many persons live in every pucca house?
- If 5000 more Kutcha houses are built, then what will be approximate change in angle for Kutcha houses in Pie Chart-I?
- If 300 families from the "Houseless" category shift into Kutcha houses, what will be the average number of families in every Kutcha house?
- What is the value of f?
- What is the median of the frequency distribution?