Percent of change Find the Original Amount

Front

What is the formula to find the original amount when given the percent of change and the new amount?

Back

Original Amount = New Amount / (1 + Percent Change) for increase, or Original Amount = New Amount / (1 - Percent Change) for decrease.

Front

If a group weighs 1,173 pounds and this is 2% heavier than their previous weight, how do you calculate their previous weight?

Back

Previous Weight = 1173 / 1.02 = 1150 pounds.

Front

Zoe's current allowance is $12.90, which is 39.9% more than her previous allowance. How do you find her previous allowance?

Back

Previous Allowance = 12.90 / 1.399 = $9.22.

Front

What does it mean when a score is 90% higher than last year's average?

Back

It means the current score is 190% of last year's average score.

Front

How do you express a 20% increase in the number of layoffs from last year?

Back

If last year there were X layoffs, then this year there are X + 0.20X = 1.20X layoffs.

Front

If a sports club has 324 members this year, which is 10% fewer than last year, how do you find last year's membership?

Back

Last Year's Membership = 324 / 0.90 = 360 members.

Front

What is the relationship between percent increase and the original amount?

Back

Percent Increase = (New Amount - Original Amount) / Original Amount * 100%.

Front

How do you convert a percentage to a decimal for calculations?

Back

To convert a percentage to a decimal, divide by 100. For example, 39.9% becomes 0.399.

Front

What is the formula for calculating percent decrease?

Back

Percent Decrease = (Original Amount - New Amount) / Original Amount * 100%.

Front

If a number is decreased by 10%, what is the factor by which you multiply the original number?

Back

You multiply by 0.90.