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A bag contains 30 white balls and 10 red balls. 16 balls are drawn one by one randomly from the bag with replacement. If X be the number of white balls drawn, then (mean of X/standard deviation of X) is equal to :(1) 4√3(2) 4√3/3(3) 4(4) 3√2 |
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Answer» Correct option (1) 4√3 Explanation: Probability of getting a white ball = 30/40 = 3/4 Probability of getting a red ball =10/40 = 1/4 n = 16 Mean = np and variance = npq So mean = 16.3/4 and s.d. = √16.3/4.1/4 So mean = 12 and s.d. = √3 so mean of x/s.d of x = 12/√3 = 4 x 3/√3 = 4√3 |
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