Percent Change Day 3:The Percent Remaining

Method

By Jim Olsen, W.I.U.#P21

For Percent Change:▲If an increase, then the percent remaining is greater than 100%. ▼If a decrease, the percent remaining is less than 100%.

Use:

(Original)*(Percent remaining) = (New)

In percent change situations, there are four numbers to pay attention to:

1. Original amount (the “old”/“starting” amount before the change)

2. New amount (the “ending” amount after the change)3. Amount of change (the difference [subtract] between

original and new)4. Percent change (percent increase or decrease).

Recall from Day 1

Put the known numbers in the chart,then figure out the others.

The Percent Remaining Method is most useful when the New amount

and the Percent change are known*.

The definition of percent change is more difficult to use because of what is known & unknown.

(*which is the first of the two harder percent change problem types)

To find the Percent Remaining, simply:▲Add on the percent to 100%, if a percent increase.

▼Subtract the percent from 100%, if a percent decrease.

Percent change is used in almost every aspect of life to describe change – and

our world is changing!

Examples:1. The attendance this year at the gym is up by 20%

since last year and currently we have 180 people per day using the gym. What was attendance last year?

Step 1: Percent remaining 100% 20% 120%

Step 2:   Original * Percent remaining New

( )(1.20) 180

180

1.2Original amount 150 people per day

x

x

x

Important Note

On the previous problem, it does not work to take 20% of the 180 (the new amount) and subtract it. The reason is that the 20% increase means 20% of the original amount (which is different from 180).

Examples:2. The sale price of the microwave is $180. This is due to

a discount of 20% from the regular price. What is the regular price?

Step 1: Percent remaining 100% 20% 80%

Step 2:   Original * Percent remaining New

( )(.80) 180

180

.80 Original price $225

x

x

x

The Percent Remaining method is also a good method when the original and percent change are known.

It saves a step of work.

As we see in the next example…

Examples:

3. This year we have $2,200 budgeted for travel expenses. For next year there is a budget cut of 8%. How much will we have for travel next year?

Step 1: Percent remaining 100% 8% 92%

Step 2:   Original * Percent remaining New

(2200)(.92)

Budget next year $2024

x

x

Closing Notes Remember

#P21

For Percent Change:▲If an increase, then the percent remaining is greater than 100%. ▼If a decrease, the percent remaining is less than 100%.

Use:

(Original)*(Percent remaining) = (New)

Stay tuned…

This is Day 3 of 4.

One more Tweets/Days will follow, with more information on percent change.

Learnist board: http://bit.ly/13AGhZq