Answer:
It will take an interest rate of 8.1% to get 150% of the initial investment in just 5 years.
Step-by-step explanation:
Use the formula for continuous compounding

where r stands for the (annual) interest rate, t for time in years, P for the initial principal (investment) and X is the amount after t years.
(this formula can be beautifully derived from just basic considerations, btw)
We are given t=5, and percent increase on the initial P, so we can solve for r

It will take an interest rate of 8.1% to get 150% of the initial investment in just 5 years.
I'd say option D because you can just tell right off the bat that if x = 0, then f(x) = 43.75.
It gained 2 lb. because if you subtract 8-6 you would get 2. So Arfus gained 2 lb.
The answer is 16 outcomes, there are two possible outcomes per classroom, and there are 8 classrooms