To solve this we are going to use the compounded interest formula: where is the final amount is the initial investment is the interest rate in decimal form is the time in years
We know that initial investment is $5,745, so . We also know that Kristen wants his investment to double, so . Now, to convert the interest rate to decimal form, we are going to divide the rate by 100%: . Since the interest is compounded monthly, it is compounded 12 times per year: therefore, . Now that we have all the information we need, lets replace the values in our formula and solve for :
We can conclude that she must leave the money for 10.7 years in the bank for it to double.
The Reason why it is 16 hours is simply because it says in the question
"The moon is around 239,000 miles from Earth. How many hours would it take a rocket that can travel at 250 MILES PER MINUTE to travel to the moon? Round to the nearest hour.
"
So, turn 16 hours into minutes, 16 X 60 = 960 X 250 miles per min = 240,000, miles there you go! the answer is B!