How To Find TIME In Simple Interest

To find time in simple interest, you have to know the formula, apply the formula and then simplify to your answer.

In this lesson, you will learn the formula and the step-by-step method for finding time in simple interest.

BONUS: A link to practice questions on simple interest is included at the end of this lesson.

Formula for finding time in simple interest

From the general formula for finding simple interest, which is​

I= \frac{PRT}{100}

Change the subject of the formula from (I) to (T) therefore making the time (T) stand alone to give the formula for finding time in simple interest.

​T= \frac{100I}{PR}

Question on finding time in simple interest

Let’s take an example:

Question:

How long will it take for #450 to yield an interest of #18 at 8% per annum?

I = #18

P = #450

R = 8%

T = ??

STEP 2.

Transfer the values into the formula

T= \frac{100×18}{450×8}

STEP 3.

Use the steps for multiplication of fractions to simplify to your answer.

• Multiply the numerators and denominators
T= \frac{1800}{3600}
• Zeros cancel Zeros
T= \frac{18}{36}
• Reduce the fraction to its lowest form
\frac{18}{36} = \frac{1}{2}