Hi i am just going over the investment word problems in purple math...does anyone have th answers for the additional examples?

Question

Hi i am just going over the investment word problems in purple math...does anyone have th answers  for the additional examples?

anonymous · Answer

post the problem on which  you want clarification.

anonymous · Answer

An investment of $3,000 is made at an annual simple interest rate of 5%. How much additional money must be invested at an annual simple interest rate of 9% so that the total annual interest earned is 7.5% of the total investment?

anonymous · Answer

"annual simple interest rate" means we can use 
rate * time* principal=amount formula

(x*.09*1)+(3,000 * .05*1)=(3000+x)*(.075)

anonymous · Answer

solve for x

anonymous · Answer

i got 500....

anonymous · Answer

close , it is 5000

anonymous · Answer

(x*.09*1)+(3,000 * .05*1)=(3000+x)*(.075)
.09x+150=225+0.075x

anonymous · Answer

oh yeah i see the mistake....thank you!

anonymous · Answer

my mistake

anonymous · Answer

thank you!