Answer:
Probability is 0.3506
Step-by-step explanation:
We are given
mean is 8mm
so, [tex]\mu=8[/tex]
standard deviation is 2.2 mm
so, [tex]\sigma=2.2[/tex]
x-varies from 7mm to 9mm
At x=7:
we can use formula
[tex]z=\frac{x-\mu}{\sigma}[/tex]
we can plug values
[tex]z=\frac{7-8}{2.2}[/tex]
[tex]z=-0.45455[/tex]
At x=9:
we can use formula
[tex]z=\frac{x-\mu}{\sigma}[/tex]
we can plug values
[tex]z=\frac{9-8}{2.2}[/tex]
[tex]z=0.45455[/tex]
So, z is between -0.45455 and 0.45455
[tex]-0.45455\leq z \leq 0.45455[/tex]
now, we can use normal distribution table
and we get
Probability is 0.3506