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Question 634366: A man makes three investments totaling $24000 with the interest rates at 6%, 7% and 8%. The total annual income is $1720, and the income from the 7% investment is $4o less than the combined income from the other investments. Find the amount of each investment.
Answer by sachi(548)   (Show Source):
You can put this solution on YOUR website! A man makes three investments totaling $24000 with the interest rates at 6%, 7% and 8%. The total annual income is $1720, and the income from the 7% investment is $4o less than the combined income from the other investments. Find the amount of each investment.
ans:-
let his investment & income out of that is as follows
investment$ rate income$
say x 6%=.06 .06x
say y 7%=.07 .07y
24000-(x+y)=z say 8%=.08 .08z
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total=24000 1720
so .06x+.07y+.08z=1720------eqn 1
& .07y+40=.06x+.08z ------eqn 2
from above 2 eqns .06x+.08z =.07y+40=1720-.07y
or 2 * .07y=1720-40=1680
or y=1680/.14=12000
now from eqn 1
.06x+.07*12000+.08(24000-x-12000)=1720
or(.06-.08)x=1720-.07*12000-.08*12000=1720-1800=-80
or -.02x=-80
or x=80/.02=4000
now z=24000-12000-4000=8000
so his invesments are $4000,$12000,$8000 (ans)
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