Answer: 13.5 hours.
I got the answer by simply adding up the integers to start with.
Integers = 1, 2, 3 and 5.
The integers added up equal to 11.
Next we add up the remaining fractions.
Fractions = 1/2, 3/4, 3/4 and 1/2.
We can add up 1/2 and 1/2 to equal 1, and 3/4 and 3/4 to make 1.5.
1 + 1.5 = 2.5
Finally, we add up the answer for the integers and the fractions together, (11 + 2.5) which equals 13.5.
Our answer is 13.5 hours.
(Not sure why the answer isn't in the choices)