Jack invested $8000, part at 10% and part at 15%. If the total interest at the end of the Yr. is $900, How?

Question

much did he invest at 10%?

I am not good at word problems help!!!

Answer 1

A simple way of approaching this...

If Jack invests all $8000 at 10% he earns $800 interest.
If Jack invests all $8000 at 15% he earns $1200 interest.

Thus for every $2000 he invests at 15% rather than 10% he earns an additional $100(equation below). You now have a ratio to work with.

($1200 - $800 = $400
$8000 / $400 is equal to $2000 / $100)

Investing all of it at 10% leaves Jack with $800... $100 short in interest, so he needs $2000 of that total invested at 15% to give him the full $900.

$8000 - $2000 = $6000

Answer: $6000 at 10% interest

There are many ways to do this, this is just an easy way of it.

Answer 2

Let's think about it. He must have invested part of the 8000 at 10%, call that X. The remainder was invested at 15%, call that Y. So:

a) X+Y=8000
b) .1X+.15Y=900

Solve the simultaneous equations:

Multiply both sides of b) by 10, giving:

c) X+1.5Y=9000

Subtract a) from c) giving:

d) .5Y=1000

Multiply both sides by 2:

(ans) Y=2000

Plug the Y value into a):

X+2000=8000

Subtract 2000 from both sides:

(ans) X=6000

Answer 3

$8000X10%=800X50years = $40,000 (Interest)
$8000X15%=900X50years = $45,000 (Interest)
I didn't know how many years did he bought ?if he bought at the years of 50 ,then the sum will be at above.if you received $900 at the end of the years that means you have cheated by the company.

Answer 4

jack was smart to invest all at double digit interest rates. with rates that high, stocks going down.

Answer 5

6000 + 2000 = 8000
0.10 -------.15
600 -------300 = 900