Let W be a random variable that is normally distributed. If the probability of W being less than 40 is 1/6

and 70 is two standard deviations above the mean, which of the following is the best estimate for the mean of W?

How do I do this?

Let W be a random variable that is normally distributed. If the probability of W being less than 40 is 1/6

and 70 is two standard deviations above the mean, which of the following is the best estimate for the mean of W?

How do I do this?

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since 1/6 is 16% that is 2 sd below the mean so

40= mean-2SD

70=mean+2SD

solve for mean

mean=55

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@prakithgre, wouldnâ€™t 1/6 or 16% be 1 st dev below mean

So approximately:

mean - st dev = 40

mean + 2 st dev = 70

2mean - 2 st dev = 80

3 mean = 150

mean = 50

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Yup sorry my bad your solution is correct

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