Answer:
The minimum head breadth that will fit the clientele is 4.4 inches.
The maximum head breadth that will fit the clientele is 7.8 inches.
Step-by-step explanation:
Let <em>X</em> = head breadths of men that is considered for the helmets.
The random variable <em>X</em> is normally distributed with mean, <em>μ</em> = 6.1 and standard deviation, <em>σ</em> = 1.
To compute the probability of a normal distribution we first need to convert the raw scores to <em>z</em>-scores using the formula:
![z=\frac{x-\mu}{\sigma}](https://tex.z-dn.net/?f=z%3D%5Cfrac%7Bx-%5Cmu%7D%7B%5Csigma%7D)
It is provided that the helmets will be designed to fit all men except those with head breadths that are in the smallest 4.3% or largest 4.3%.
Compute the minimum head breadth that will fit the clientele as follows:
P (X < x) = 0.043
⇒ P (Z < z) = 0.043
The value of <em>z</em> for this probability is:
<em>z</em> = -1.717
*Use a <em>z</em>-table.
Compute the value of <em>x</em> as follows:
![z=\frac{x-\mu}{\sigma}\\-1.717=\frac{x-6.1}{1}\\x=6.1-(1.717\times 1)\\x=4.383\\x\approx4.4](https://tex.z-dn.net/?f=z%3D%5Cfrac%7Bx-%5Cmu%7D%7B%5Csigma%7D%5C%5C-1.717%3D%5Cfrac%7Bx-6.1%7D%7B1%7D%5C%5Cx%3D6.1-%281.717%5Ctimes%201%29%5C%5Cx%3D4.383%5C%5Cx%5Capprox4.4)
Thus, the minimum head breadth that will fit the clientele is 4.4 inches.
Compute the maximum head breadth that will fit the clientele as follows:
P (X > x) = 0.043
⇒ P (Z > z) = 0.043
⇒ P (Z < z) = 1 - 0.043
⇒ P (Z < z) = 0.957
The value of <em>z</em> for this probability is:
<em>z</em> = 1.717
*Use a <em>z</em>-table.
Compute the value of <em>x</em> as follows:
![z=\frac{x-\mu}{\sigma}\\1.717=\frac{x-6.1}{1}\\x=6.1+(1.717\times 1)\\x=7.817\\x\approx7.8](https://tex.z-dn.net/?f=z%3D%5Cfrac%7Bx-%5Cmu%7D%7B%5Csigma%7D%5C%5C1.717%3D%5Cfrac%7Bx-6.1%7D%7B1%7D%5C%5Cx%3D6.1%2B%281.717%5Ctimes%201%29%5C%5Cx%3D7.817%5C%5Cx%5Capprox7.8)
Thus, the maximum head breadth that will fit the clientele is 7.8 inches.