Question 1110343
z<(72.5-73)/0.8 or z<-0.625.  General form for z is (x-mean)/s.d.
probability is 0.2660.  Yours should be close enough, since you used -0.62. Apparently, they did not want z rounded at all.

For 36 cars, z < (x bar-mean)/0.8/sqrt(36)
This is -0.5*6/0.8=-3/.8=-3.75. That probability is 0.000088

One car's being below 72.5 would occur one time out of four.  It should not be a cause for alarm in this instance.

Probability can never be negative or greater than 1.  The last ne is the probability that this deviation is random is very small.  It is extraordinarily small.