What is BD?
C
X + 5
B
х
12
27
А
BD =

This Question Can't be anwsered, Because there is nothing on the right hand side of the equation.

Hello!

The words at least means that the worker needs to work 8, 9 or 10 hours. We can add probabilities, so we will add .6 (for those working 8 hours), .15 (for those working 9 hours) and .08 (for those working 10 hours) to get a total probability of .83.
Hope this helps!