PLease Help me to graduate

1- Given standard normal distribution, find

a) P(Z <-2.33)

b) P(Z> 1.99)

C) P(-1.25 <Z<1.75)

2 Given standard normal distribution, find the z-score that

a) has 33% of the distribution's area to the right

b) corresponds to P5 (the 5th percentile);

c) has 75% of the distribution's area between -z and z.

3. The numbers of hours worked by medical residents is approximately normally distributed with a mean of 81.7 hours and a standard deviation of 6.9 hours.

a) What proportion of medical residents work less than 70 hours per week?

b) If 500 medical residents are selected, how many can be expected to work between 75 and 95 hours in a week?

c) What is the probability that a medical resident works more than 100 hours per week?

d) if the bottom 10% are excluded, what is the cut-off number of hours worked per week in order to be included?

e) what value of the number of hours worked per week represents the third quartile?