** Need help with #3 **

The expected project completion time for the construction of a pleasure yacht is 21 months and the project variance is 6. questions (Note: when using the Z tables round your Z values to two decimal places before getting the probabilities from the tables. DO NOT round standard deviations prior to calculating Z values)

1) What is the probability that the project will require at least 17 months? (Enter 4 decimal places) 0.9487

2) What is the probability that the project will be completed within 20 months? (Enter 4 decimal places) 0.3416

3) What is the probability that the project will require at least 23 months? (Enter 4 decimal places)

4) What is the probability that the project will be completed within 25 months? (Enter 4 decimal places) 0.9487

5) What is the probability that the project will take between 17 and 23 months to complete? (Enter 4 decimal places) 0.7423