SOLUTION: on January 1, Mr. Warner and his son jointly invest a sum of money at an annual rate of 6.75%. On January 1 of the following year, their total investment is worth $5978. If Mr. War

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: on January 1, Mr. Warner and his son jointly invest a sum of money at an annual rate of 6.75%. On January 1 of the following year, their total investment is worth $5978. If Mr. War      Log On


   

Question 389825: on January 1, Mr. Warner and his son jointly invest a sum of money at an annual rate of 6.75%. On January 1 of the following year, their total investment is worth $5978. If Mr. Warner invested $4500 of his own money, how much money did his son invest?
I know the answer is $1100 but I don't know why it's $1100???
Thanks.
Found 2 solutions by josmiceli, mananth:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = amount his son invested
given:
Mr Warner invested 4500
------------------
After 1 year,
4500+%2B+x+%2B+.0675%2A%284500+%2B+x%29+=+5978
4500+%2B+x+%2B+303.75+%2B+.0675x+=+5978
1.0675x+=+5978+-+4500+-+303.75
1.0675x+=+5978+-+4803.75
1.0675x+=+1174.25
x+=+1100
His son invested $1,100

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
on January 1, Mr. Warner and his son jointly invest a sum of money at an annual rate of 6.75%. On January 1 of the following year, their total investment is worth $5978. If Mr. Warner invested $4500 of his own money, how much money did his son invest?
...
let them investtogether $x
Warner invests 4500
Son invests x-4500
..
Interest in 1 year = 5978-x
..
Total investment =x
6.75x= 100*(5978-x)
6.75x=597800-100x
106.75x=597800
x=597800/106.75
They invested $ 5600.00
son invested 5600-4500
= $1100
..
m.ananth@hotmail.ca