The mean and variance of n observations are 8 and 16, respectively. If the sum of the first (n−1) observations is 48 and the sum of squares of the first (n−1) observations is 496, then the value of n is:
Held on 2 Apr 2026 · Verified 6 Jul 2026.
21
16
13
7
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Let the mean and the variance of seven observations $2, 4, \alpha, 8, \beta, 12, 14$, $\alpha < \beta$, be $8$ and $16$ respectively. Then the quadratic equation whose roots are $3\alpha + 2$ and $2\beta + 1$ is :
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Work through every JEE Main Probability & Statistics PYQ, year by year.