HELP FOR A MEDAL!! ms.Campbell invested $7200 for 2 1/2 years. If she earned $756, at what rate(R) did she invest her money?

Question

vocaloid · Answer

money earned = (investment)*(1+rate/100)^time

vocaloid · Answer

plug in your numbers and solve for r

anonymous · Answer

I did ....7200=(756) (?) (2 1/2)  I=PRT

anonymous · Answer

I multiplied (756) * (2 1/2) and got 1890 and then divide 7200/ 1890 and got 3.8095238 it's wrong :(

vocaloid · Answer

756 = (7200)(1+rate/100)^(2.5)

vocaloid · Answer

(756/7200) = (1+rate/100)^2.5

vocaloid · Answer

(756/7200)^(1/2.5) = 1 + rate/100

vocaloid · Answer

(756/7200)^(1/2.5) - 1 = rate/100

anonymous · Answer

I got 0.042

vocaloid · Answer

oh, whoops, small mistake on my part

money earned = 7200+756

([7200+756]/7200)^(1/2.5) - 1 = rate/100
solve for rate

anonymous · Answer

Hmmm would it be cross multiply 1.105 1/2.5 ?? :)