21-4 Refine

A student does 50 minutes of homework on Monday and 30 minutes of homework on Tuesday. What is the percent decrease in homework time from Monday to Tuesday?

The boiling point of water is 212 degrees F at sea level. Andres lives at an elevation of 7,500 ft. At his home, Andres finds that water boils at 198 degrees F. What is the percent decrease in the boiling point of water from sea level to 7,500 ft? Give your answer to the nearest tenth of a percent. Show your work.

Each summer, a school offers a trip to Washington, D.C. Last summer, 80 students signed up for the trip. This summer, 94 students signed up for the trip. To the nearest percent, what is the percent change in the number of students who signed up for the trip?

• 2%

• 14%

• 15%

• 18%

Elena uses jars to store her craft supplies. She estimates that each jar will fit 1,000 buttons or 50 large beads. Each jar actually fits 677 buttons or 22 large beads. To the nearest percent, what is the percent error of the estimate for the buttons?

Elena uses jars to store her craft supplies. She estimates that each jar will fit 1,000 buttons or 50 large beads. Each jar actually fits 677 buttons or 22 large beads. To the nearest percent, what is the percent error of the estimate for the beads?

Choose the following that describe a percent increase.

• The cost of a hat was $12 and is now $15.

• A person's height changes from 52 in. to 61 in.

• The temperature falls from 20 degrees to 16 degrees.

• n changes to .75n

Most days, Mr. Romano sells umbrellas for $8. On rainy days, he increases the price by 75%. How much does he charge, in dollars, for an umbrella on rainy days?