Robby invested $18,400 at 7% interest. He earned $9016 interest at the end of x years.

What is the value of x?

A.
10

B.
9

C.
8

D.
7

Question

Robby invested $18,400 at 7% interest. He earned $9016 interest at the end of x years. 

What is the value of x?
	
	
 
A.
	10
	
 
B.
	9
	
 
C.
	8
	
 
D.
	7

anonymous · Answer

I don't which one is principal, rate, or interest! :c

seratul · Answer

http://openstudy.com/updates/54d63d96e4b04a1cb35406e2 Someone already had this question. Hope this helps! The answer would be 7

mathmale · Answer

"Robby invested $18,400."  The amount he originally invests is your principal, P.

 "7% interest."        Interest rates are sometimes (not always) expressed as percentages, like this 7%.  If so, you must convert the percentage to a decimal fraction.
What is the decimal equivalent of 7%?

" interest:"  Not the same thing as "7% interest," above.  Rather, "interest" standinga lone means the amount of income your investment earns over time.

Here it's how much your principal, invested at 7%, would earn over x years.

You are told that the interest earned was $9016.

The pertinent equation for interest is

i = p*r*t, where t is the number of years over which the principal, p, earns interest.

anonymous · Answer

Thanks so much @mathmale !

mathmale · Answer

My great pleasure!  It feels nice to be appreciated.