Check my work. Please!! The formula for determining interest compounded monthly is A = P(1 +r/12)^12t, where A represents the amount invested after t years, P the principal invested, and r the interest rate. Jimmy invests $1,000 at an interest rate of 10% for 3 years, while Jenny invests $1,000 at an interest rate of 5% for 6 years. Determine the amount of return gained by Jimmy and Jenny. In complete sentences, summarize your results.

Question

anonymous · Answer

Jimmy:  A=$1,000(1+.1/12 )^36 =$1,346.18
Jenny:  A = $1,000(1 +.05/12)^7=$4,413.15
Jimmy gains: $1,346.18-1,000 =$346.18
Jenny gains:  $4,413.15-1,000=$3,413.15

anonymous · Answer

Yay! So is my work right?!

anonymous · Answer

hjmmmmmm

anonymous · Answer

wait

anonymous · Answer

some of the answers are off for sure

anonymous · Answer

Well can you help me fix them?? I'm so confused.

anonymous · Answer

Jenny: A = $1,000(1 +.05/12)^7=$4,413.15  is wrong

anonymous · Answer

10% is 0.1

anonymous · Answer

Yes then I subtracted 1,000 for the answer?

anonymous · Answer

the exponent should be $30$

anonymous · Answer

why

anonymous · Answer

and the calculation was also wrong, you must have entered it in the calculator incorrectly

anonymous · Answer

you can't invest $1000 at 5% for 6 years and make $4000!

anonymous · Answer

should be 
$$A=1000\times (1+\frac{.05}{12})^{12\times 6}$$

anonymous · Answer

or 
$$A=1000\left(1+\frac{.05}{12}\right)^{72}$$

anonymous · Answer

its about $1349 http://www.wolframalpha.com/input/?i=1000%281%2B.05%2F12%29^72

anonymous · Answer

that was jenny

anonymous · Answer

Jenny**

anonymous · Answer

first one looks right, i will check it

anonymous · Answer

i am getting $1348 for the first one, but it is close http://www.wolframalpha.com/input/?i=1%2C000%281%2B.1%2F12+%29^36+

anonymous · Answer

i think you had the right formula and just entered it in to the calculator wrong for jenny

anonymous · Answer

you wrote the exponent as 7 but i assume that was a typo and you meant 72
it is easy to make a mistake when calculating this 
not sure what calculator you use

anonymous · Answer

Okay so other than that it's right? THANK YOU!! :D :D :D

anonymous · Answer

yes, take a look at the links i sent
wolfram is real easy to use
just type it in (i cut and paste what you wrote) and you get the answer

anonymous · Answer

yw