Answer:
The $9000 investment was at 5.5% interest and $7000 investment was at 5% interest rate.
Step-by-step explanation:
Let x% interest rate is applicable to the $9000 investment.
So, the interest earned in one year from this investment is [tex]\frac{9000 \times x}{100} = 90x[/tex]
Again, assume that the interest rate of $7000 investment y%.
So, the interest earned in one year from this investment is [tex]\frac{7000 \times y}{100} = 70y[/tex]
By the condition given, 90x - 70y = 145 ....... (1)
Now, the $7000 is invested at a 0.5% lesser rate of interest than the $9000.
Hence, x - y = 0.5 ......... (2)
⇒ 70x - 70y = 35 ............ (3)
Now, solving equations (1) and (3) we get,
90x - 70x = 145 - 35 = 110
⇒ 20x = 110
⇒ x = 5.5%
So, from equation (2) we get, y = x - 0.5 = 5.5 - 0.5 = 5%
Therefore, the $9000 investment was at 5.5% interest and $7000 investment was at 5% interest rate. (Answer)
