Aspect ratio

Movies and the screens we view them on typically come in two formats. Standard format has a 3:4 aspect ratio, meaning that the picture height is ³/₄ of the picture width. Widescreen format has a 9:16 aspect ratio, so the picture height is ⁹/₁₆ of the picture width. A widescreen movie shown on a standard screen has two horizontal black bars, one above and one below the picture. Likewise, a standard movie shown on a widescreen screen has vertical black bars on the sides. What percent of the viewing area is lost to the black bars when viewing a widescreen movie on a standard screen? How about when viewing a standard movie on a widescreen screen?

Stock Up

Walter buys shares of a stock for $1000 on Monday. On Tuesday, the stock gains 10%. On Wednesday it loses 10%. What is the value of the stock at the end of trading on Wednesday?

Good Pi

A common approximation of π is ²²/₇ = 3.142857. Using 3.141593 as the value of π, compute the percent error introduced by using ²²/₇  instead.

Volume Tolerance

Each side of a cube must measure 1.00 inches ± 1%. What will be the percent tolerance for the volume?

Gasoline Prices

Click the image to see it full-size.

Based on the graph above, which state has the highest average gasoline price? Which state the lowest? What is the percent increase from lowest to highest?

Discounted Discount

Paul found a pair of trousers on the clearance rack discounted 80%. He also had a coupon that entitled him to an additional 15% off. He took the trousers to the checkout expecting to get 95% off. What mistake did Paul make? What was the actual discount Paul received?

Minnesota Voters

The Minnesota Secretary of State estimates that 3,799,328 Minnesotans were eligible to vote in a recent election. 55.46% of eligible voters cast ballots. About how many voters went to the polls? Round to four significant digits.

County Voters

For a recent election, there were 3,128,681 voters registered in Minnesota. Of those voters, 706,153 were registered in Hennepin County. What percent of voters were registered in Hennepin County? Round to the nearest whole percent.

Fat Calories

A hamburger from a popular chain contains 670 calories and has 40 grams of fat. There are 9 calories in a gram of fat. What percent of the calories in the hamburger are from fat?

Milk Prices

From January 1 to February 1 the price of milk at the local grocery store increased from $2.89 per gallon to $3.29 per gallon. What was the percent of increase?