The simple interest on an investment of $4000 for one year is $140.

What is the interest rate?

A.
0.035%

B.
3.5%

C.
35%

D.
350%

Question

The simple interest on an investment of $4000 for one year is $140. 

What is the interest rate?
 
 A.
0.035%
 
 B.
3.5%
 
 C.
35%
 
 D.
350%

anonymous · Answer

@timaashorty

mathmale · Answer

You could easily look up the formula for "simple interest."

It's i=Prt, where i is the interest, in dollars, P is the principal, in dollars, r is the interest rate (as a decimal fraction), and t is the time (in years).

Start with i=Prt.

Solve this for r, algebraically.
           ?
r= ---------- = ??
            ?

anonymous · Answer

I tried studying simple interest but its so hard.

mathmale · Answer

Again, the formula for simple interest is i=Prt.

Divide both sides of that equation by Pt.

What do you get as a result?  r = ?

timaashorty · Answer

140 / 40000 * 100 = 3.5%

I would take you step by step buts complicated ion my phone. And consider what math ale said. Err I can't view my text anyways l

timaashorty · Answer

Got to go. Sorry if that sounded confusing

mathmale · Answer

$$i = P r t$$
Divide both sides by P:

 i         P r t
--- = ------ = ?
P          P

anonymous · Answer

I think I get it thanks

mathmale · Answer

You'll still need to divide both sides by t also.

Once you have a formula for r, substitute the known quantities and calculate the actual value of r.

timaashorty · Answer

Yes, as long as you have 
That formuLa memorized calculating interest will rate be pretty simple.