91影视

The men鈥檚 heights are normally distributed with a mean of 68.6 in and a standard deviation of 2.8 in.

The Mickey Mouse character must have a height between 56 in and 62 in.

Let X be the height of the men.

Then,

$$\begin{gathered} X~\text{N}\left(渭,{蟽}^2\right) \\ \text{鈭糔}\left(68.6,{2.8}^2\right) \end{gathered}$$

a.

The z-score is the standardized score for a specific value. It is computed as follows.

$z=\frac{x-渭}{蟽}$

The z-score associated with the heights 56 in and 62 in are as follows.

$$\begin{gathered} z_1=\frac{56-68.6}{2.8} \\ =-4.5 \\ {z}_2=\frac{62-68.6}{2.8} \\ =-2.3571 \end{gathered}$$

From the standard normal table, find the cumulative probabilities associated with each z-score.

In the standard normal table, the cumulative probability is obtained.

For the z-score -4.5 corresponding to row -4.5 and column 0.00, it is 0.0001.

For the z-score -2.36 corresponding to row -2.3 and column 0.06, it is 0.0091.

Thus,

$$\begin{gathered} P\left(Z<-4.5\right)=0.0001 \\ P\left(Z<-2.36\right)=0.0091 \end{gathered}$$

The probability that the height of a randomly selected man lies between 56 in and 62 in is

$$\begin{gathered} P\left(56<X<62\right)=P\left(-4.5<z<-2.36\right) \\ =P\left(Z<-2.36\right)-P\left(Z<-4.5\right) \\ =0.0091-0.0001 \\ =-0.0090 \end{gathered}$$

Then, the percentage of the men meeting the height requirement is$-0.009脳100=-0.90\%$.

Therefore, only of the men meet the height requirement, which is quite less. Therefore, it is more likely that most Mickey Mouse characters are women.

b.

The new height requirement excludes the tallest 50% and the shortest 5% men.

Let the minimum height of the tallest 50% men be $x_1\left(z_1\right)$, and the maximum height of the shortest 5% men be $x_2\left(z_2\right)$.

Thus,

$$\begin{gathered} P\left(X<x_2\right)=0.05 \\ P\left(Z<z_2\right)=0.05 \\ P\left(X>x_1\right)=0.5 \\ P\left(Z>z_1\right)=0.5 \end{gathered}$$

From the standard normal table, the values of the z-scores are obtained as follows.

The cumulative area of 0.05 corresponds to the row to -1.6 and 0.045, which implies the z-score of -1.645.

The cumulative area of 0.5 corresponds to the row to 0.0 and 0.00, which implies the z-score of 0.

The minimum height for the shortest 5% of the men is computed as follows.

$$\begin{gathered} z_1=\frac{x_1-68.6}{2.8} \\ -1.645=\frac{x_1-68.6}{2.8} \\ {x}_1=63.994\text{in} \end{gathered}$$

The minimum height for the tallest 50% of the men is computed as follows.

$$\begin{gathered} z_2=\frac{x_2-68.6}{2.8} \\ 0=\frac{x_2-68.6}{2.8} \\ {x}_2=68.6\text{in} \end{gathered}$$

Thus, the shortest 5% of the men are shorter than 64.0 in, and the tallest 50% of the men are taller than 68.6 in. The new height requirements are between 64.0 in and 68.6 in.