SOLUTION: investments: An investor has a total of 25,000 deposited into three diffrent accounts, which earn annual interest rate of 8%, 6%, and 4%. The amount deposited in the 8% account is

Algebra ->  Finance -> SOLUTION: investments: An investor has a total of 25,000 deposited into three diffrent accounts, which earn annual interest rate of 8%, 6%, and 4%. The amount deposited in the 8% account is       Log On


   



Question 165151This question is from textbook
: investments: An investor has a total of 25,000 deposited into three diffrent accounts, which earn annual interest rate of 8%, 6%, and 4%. The amount deposited in the 8% account is twice the amount in the 6% account. If the three accounts earns total annual interest of $1520, how much money is deposited into each account? This question is from textbook

Found 2 solutions by josmiceli, padmameesala:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a= amount invested @ 8%
Let b= amount invested @ 6%
Let c= amount invested @ 4%
It is given that
(1) a+%2B+b+%2B+c+=+25000
(2) .08a+%2B+.06b+%2B+.04c+=+1520 annually
(3) a+=+2b
This is 3 equations and 3 unknowns, so it should
be solvable
Multiply both sides of (2) by 100
(2) 8a+%2B+6b+%2B+4c+=+152000
Multiply both sides of (1) by 4 and
subtract from (2)
(1) 4a+%2B+4b+%2B+4c+=+100000
(4) 4a+%2B+2b+=+52000
Since a+=+2b
(4) 4%2A%282b%29+%2B+2b+=+52000
(4) 10b+=+52000
b+=+5200
a+=+2b
a+=+10400
and
(1) a+%2B+b+%2B+c+=+25000
(1) 10400+%2B+5200+%2B+c+=+25000
c+=+25000+-+15600
c+=+9400
$10,400 was invested @ 8%
$5,200 was invested @ 6%
$9,400 was invested @ 4%
check:
(1) a+%2B+b+%2B+c+=+25000
(1) 10400+%2B+5200+%2B+9400+=+25000
25000+=+25000
(2) .08a+%2B+.06b+%2B+.04c+=+1520
(2) .08%2A10400+%2B+.06%2A5200+%2B+.04%2A9400+=+1520
(2) 832+%2B+312+%2B+376+=+1520
1520+=+1520
(3) a+=+2b
{3) 10400+=+2%2A5200
(3) 10400+=+10400
OK

Answer by padmameesala(42) About Me  (Show Source):
You can put this solution on YOUR website!
Let the amounts in three different accounts be x,y,z respectively.
Then x + y + z = 25000 ------------(1)
and annual interest of x is 8%
y is 6%
z is 4%
The amount deposited in the 8% account is twice the amount in the 6% account.
That is x=2y --------------------(2)
the three accounts earns total annual interest of $1520
that gives 8%x + 6%y + 4%z = 1520
8x + 6y + 4z = 152000
4x + 3y + 2z = 76000 --------------(3)
Solving the 3 eqns for x,y,z
plug x=2y in eqns 1 and 3
3y + z = 25000 ----------(4)
11y + 2z = 76000 ----------(5)
subtract eqns (5) and 2* eqn (4)
5y = 26000
y = 5200
x = 10400 from eqn (2)
and z = 9400 from eqn (1)
The money deposited in the 3 accounts is 10400, 5200 and 9400