Question

The length of a screw produced by a machine is normally distributed with a mean of 0.25 inches and a standard deviation of 0.01 inches. What percent of screws are between 0.24 and 0.26 inches?

68%

95%

99.7%

100%

Answer 1

@maimigirl

Answer 2

\[\begin{align*}P(0.24<X<0.26)&=P\left(\frac{0.24-0.25}{0.01}<\frac{X-0.25}{0.01}<\frac{0.26-0.25}{0.01}\right)\\\\
&=P(-1<Z<1)
\end{align*}\]
How much of a population lies within one standard deviation from the mean?

Answer 3

i was doing such type of questions very recently.
population that lies within one standard deviation from the mean is 68%