The answer is 85 miles/hour. Hope it helps! If you could vote me brainiest, that would be awesome, thanks!
Answer:
Probability is 0.3506
Step-by-step explanation:
We are given
mean is 8mm
so, 
standard deviation is 2.2 mm
so, 
x-varies from 7mm to 9mm
At x=7:
we can use formula

we can plug values


At x=9:
we can use formula

we can plug values


So, z is between -0.45455 and 0.45455

now, we can use normal distribution table
and we get
Probability is 0.3506
6.78*10^3 (10 to the third power)