Answer:
the answer is: 64.9 but I'm not sure
B. 5 cm, 6 cm, 7 cm . because the sum of two sides should be greater then the 3rd side
--------------------------------------------
Question
--------------------------------------------

--------------------------------------------
Convert the fractions to decimals
--------------------------------------------

--------------------------------------------
Evaluate each term
--------------------------------------------

--------------------------------------------
Add them up
--------------------------------------------

--------------------------------------------
Answer : 3610.201--------------------------------------------
The probability density function (pdf) is;
f(x)=
for a ≤ x ≤ b.
while the mean is given as 
And the standard deviation given as 
It should be 9:30 P.M.
7:45+ 15= 8
1 hour 35 minutes - 15= 1 hour 20
8+ 1 hour 20 minutes= 9:20
9:20+ 10= 9:30 P.M.