If the heights of 300 students are normally distributed with mean 68.0 inches an

Question

If the heights of 300 students are normally distributed with mean 68.0 inches and standard deviation 3.0 inches,

how many students have heights (a) greater than 72 inches, (b) less than or equal to 64 inches, (c) between 65

and 71 inches inclusive, (d) equal to 68 inches? Assume the measurements to be recorded to the nearest inch.

I did A and D, but i couldn't do B and C

PLZZZ NEEED HELP !

FULLY EXPLAIN = Life Saver

Explanation / Answer

Given X~Normal(mean=68, s=3) ------------------------------------------------------------------------------ a) Greater than 72 inches P(X>72) = P((X-mean)/s > (72-68)/3) =P(Z> 1.33) = 0.0917 (check standard normal table) So n=300* 0.0917 = 27.51 Take n=28 ------------------------------------------------------------------------------ b) Less than or equal to 64 inches P(X

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