Question

Nico is saving money for his college education. He invests some money at 9?%, and ?$1500 less than that amount at 6 %. The investments produced a total of ?$225 interest in 1 yr. How much did he invest at each? rate?

He invested ?$(blank) nothing at 9?% and ?(blank) nothing at 6?%.

Answer 1

concept: Formula for interest for n year , if P DOLLARS ARE INVESTED IS

Interest = P * r * t /100 ; where P is the initial amount invested, r is the rate at which the amount is invested, t is the time for which the interest is being calculated.

Now, Inthis question Nico has invested in two different investment

Assume first investment is of $ P at 9% rate

So second investment will be of $ (P - 1500) @ 6% rate

Now both investment is for 1 year.

Hence, interest number 1 = P*9*1 /100

Interest number 2 = (P -1500)* 6 * 1/ 100

Now it is given that Total interest = 225

So,. => Interest number 1 + interest number 2 = 225

=> (9P/100) + [(P - 1500)] *6/100 = 225

Solving the equation we will get P = $ 2100.

So first investment was P = $ 2100 and second was $ (2100-1500) = $ 600

So He invested $ 2100 at 9% and $600 at 6%.