Question

The time required to complete a project is normally distributed with a mean of 80 weeks and a standard deviation of 10 weeks. The construction company must pay a penalty if the project is not finished by the due date in the contract. If a construction company bidding on this contract wishes to be 90 percent sure of finishing by the due date, what due date (project week #) should be negotiated?

Answer 1

Answer: the due date would be 92 weeks

Step-by-step explanation:

Since the time required to complete a project is normally distributed, we would apply the formula for normal distribution which is expressed as

z = (x - µ)/σ

Where

x = number of weeks.

µ = mean

σ = standard deviation

From the information given,

µ = 80 weeks

σ = 10 weeks

If a construction company bidding on this contract wishes to be 90 percent sure of finishing by the due date, the z score corresponding to 90%(90/100 = 0.9) is 1.29

Therefore,

1.29 = (x - 80)/10

x - 80 = 1.2 × 10

x - 80 = 12

x = 80 + 12 = 92