Percent Change (Increase or Decrease)

In this video, we will be learning how to determine percent change.

Percent Change Formula: $\dfrac{New Value - Original Value}{Original Value}\cdot100\%=Percent Change$

For example:

The price of gas was originally $5. The new price for gas is $4. What is the percent change?

$\dfrac{New Value - Original Value}{Original Value}\cdot100\%=Percent Change$

$\dfrac{(4) - (5)}{(5)}\cdot100\%=Percent Change\leftarrow$ Substitute the givens

$\dfrac{(4) - (5)}{(5)}\cdot100\%=Percent Change\leftarrow$ Simplify

$\dfrac{-1}{5}\cdot100\%=Percent Change$

$-20\%=Percent Change$

Video-Lesson Transcript

In this video, we will be learning how to determine percent change.

Let’s go through percent increase or percent decrease.

We will use just one formula to compute the percent change:

$\dfrac{New Value - Original Value}{Original Value} \times 100\%$

For example:

The price of gas was originally $\$5$ . The price went down to $\$4$ . What is the percent change?

Let’s use the formula to determine the percent change.

$\dfrac{4 - 5}{5} \times 100\%$

Which will be $\dfrac{(- 1)}{5} \times 100\%$

Then divide $(- 1)$ by $5$ the answer is $(- 0.20)$

$(- 0.20) \times 100\% = (-20\%)$

We have a $20\%$ decrease

Let’s have another one.

The price of gas was originally $\$4$ . The price went down to $\$5$ . What is the percent change?

Let’s use the formula and substitute all the given values.

$\dfrac{5 - 4}{4} \times 100\%$ $\dfrac{1}{4} \times 100\%$ $0.25 \times 100\%$

We’ll get $25\%$

Since the answer is positive, it means it’s an increase.

Just a review, the percent change formula is

$\dfrac{New Value - Original Value}{Original Value} \times 100\%$