JEE Main 2026 Mathematics question
A set of four observations has mean 1 and variance 13. Another set of six observations has mean 2 and variance 1. Then, the variance of all these 10 observations is equal to:
Answer: (C)
Solution
Combined mean=(4·1+6·2)/10=1.6. Σx² for the first set=4(13+1)=56 and for the second=6(1+4)=30, so Σx²=86. Variance=86/10−1.6²=8.6−2.56=6.04.