Q90. From a lot of 12 items containing 3 defectives, a sample of 5 items is drawn at random. Let the random variable X denote the number of defective items in the sample. Let items in the sample be drawn one by one without replacement. If variance of $X$ is $\frac { m } { n }$, where $\operatorname { gcd } ( m , n ) = 1$, then $n - m$ is equal to $\_\_\_\_$ t
Q90. From a lot of 12 items containing 3 defectives, a sample of 5 items is drawn at random. Let the random variable X denote the number of defective items in the sample. Let items in the sample be drawn one by one without replacement. If variance of $X$ is $\frac { m } { n }$, where $\operatorname { gcd } ( m , n ) = 1$, then $n - m$ is equal to $\_\_\_\_$ t
\section*{ANSWER KEYS}
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1. (2) & 2. (1) & 3. (3) & 4. (2) \\
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9. (2) & 10. (2) & 11. (4) & 12. (4) \\
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17. (3) & 18. (2) & 19. (3) & 20. (3) \\
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25. (93) & 26. (160) & 27. (100) & 28. (10) \\
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33. (3) & 34. (2) & 35. (2) & 36. (3) \\
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41. (4) & 42. (3) & 43. (1) & 44. (3) \\
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