Percent Change and Percent Error

Front

What is percent change?

Back

Percent change is a way to express a change in a quantity as a percentage of the original amount. It is calculated using the formula: ((New Value - Old Value) / Old Value) x 100.

Front

How do you calculate a discount?

Back

To calculate a discount, multiply the original price by the discount rate (as a decimal) and subtract that amount from the original price. Formula: Final Price = Original Price - (Original Price x Discount Rate).

Front

What is the formula for percent error?

Back

Percent error is calculated using the formula: Percent Error = |(Actual Value - Estimated Value)| / Actual Value x 100.

Front

If a shirt costs $50 and is on sale for 20% off, what is the sale price?

Back

Sale Price = $50 - ($50 x 0.20) = $40.

Front

What does it mean to round to the nearest tenth of a percent?

Back

Rounding to the nearest tenth of a percent means adjusting a percentage to one decimal place, for example, 7.89% becomes 7.9%.

Front

How do you find the final price after tax?

Back

To find the final price after tax, multiply the price before tax by (1 + tax rate). For example, if the price is $100 and tax is 5%, Final Price = $100 x (1 + 0.05) = $105.

Front

What is a coupon discount?

Back

A coupon discount is a reduction in price offered by a retailer, usually expressed as a percentage off the original price.

Front

If a student estimates a length to be 30 inches, but the actual length is 50 inches, what is the percent error?

Back

Percent Error = |(50 - 30)| / 50 x 100 = 40%.

Front

What is the difference between actual value and estimated value?

Back

Actual value is the true measurement or value, while estimated value is an approximation or guess of that measurement.

Front

How do you calculate an increase in earnings?

Back

To calculate an increase in earnings, multiply the original earnings by the increase rate (as a decimal) and add that to the original earnings. Formula: New Earnings = Original Earnings + (Original Earnings x Increase Rate).