JEE Main 2026 Mathematics question
For 10 observations x₁,…,x₁₀, if and , then their standard deviation is:
Answer: (D)
Solution
Expanding gives ΣX²+4ΣX=140 and ΣX²−2ΣX=80. Solving: ΣX=10 (mean=1), ΣX²=100. Variance = 100/10 − 1 = 9, SD = 3.
For 10 observations x₁,…,x₁₀, if and , then their standard deviation is:
Expanding gives ΣX²+4ΣX=140 and ΣX²−2ΣX=80. Solving: ΣX=10 (mean=1), ΣX²=100. Variance = 100/10 − 1 = 9, SD = 3.