Can someone help me with this question? 

Q94-Together with your team, you applied three-point estimation on a critical path

which consists of two activities.

The following duration uncertainties are all calculated assuming a ±3sigma 

confidence interval.

The duration uncertainty—defined as pessimistic minus optimistic estimate—of 

the first activity is 18 days; the second estimate has an uncertainty of 24 days. 

Applying the PERT formula for paths, what is the duration uncertainty of the