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If the heights of 300 students are normally distributed with mean 68 inches and standard deviation 3 inches. If Z is the standard normal variate such that P(0≤Z≤1.33)=0.4082,P(Z≥1.33)=0.0918P(0\le Z\le 1.33)=0.4082, P(Z\ge 1.33)=0.0918 and P(0≤Z≤1)=0.3413P(0\le Z\le 1)=0.3413, then which of the following statements are correct?

(A) There are 27 students whose height is greater than 72 inches.

(B) The number of students having heights less than or equal to 64 inches is 27.

(C) 210 students have their heights between 65 and 71 inches.

(D) There are 35 students whose height is greater then 72 inches.

Choose the correct answer from the options given below:

Solution

✅ Correct Option: 1

For x=72x=72, z=72−683=1.33z=\frac{72-68}{3}=1.33, so P=0.0918P=0.0918 and 300×0.0918≈27300\times0.0918\approx27. (A) true, (D) false.

By symmetry x=64x=64 gives z=−1.33z=-1.33 and the same 2727 students. (B) true.

Between 6565 and 7171, z=±1z=\pm1 gives 2×0.3413=0.68262\times0.3413=0.6826, about 205205 students, not 210210. (C) false.

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