Project Management: Critical Paths

Please help me to solve the following problem:

You are working on a project that has 12 activities. You determine that the critical path consists of only five activities. You then compute the variances for the five critical path activities and these variances are 3, 4, 2, 1, and 6 days. The desired completion date for the project is 44 days and the expected completion date for the project is 40 days. Which of the following alternatives gives the probability that the project will be completed by the desired completion date?