Activities $\text{A, B, C}$ and $\text{D}$ form the critical path for a project with a $\text{PERT}$ network. The means and variances of the activity duration for each activity are given below. All activity durations follow the Gaussian (normal) distribution, and are independent of each other.
$$\begin{array}{|cl|cI|cI|cI|cI|}\hline
&\text{Activity} & \text{A} & \text{B} & \text{C} & \text{D} \\ \hline &\text{Mean (days)} & \text{6} & \text{11} & \text{8} & \text{15} \\ \hline &\text{Variance (days$^{2})$} & \text{4} & \text{9} & \text{4} & \text{9}\\ \hline \end{array}$$
The probability that the project will be complete within $40$ days is ________________ ($\textit{round off to two decimal places}$).
($\text{Note}$: Probability is a number between $0$ and $1$).