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IM: 7.4.14: Percent Error (Lesson)

By Newsela Staff
Last updated 6 days ago
13 Questions
14.1: Number Talk: Estimating a Percentage of a Number
Estimate.

25% of 15.8

9% of 38

1.2% of 127

0.53% of 6

0.06% of 202

14.2: Plants, Bicycles, and Crowds

Instructions to care for a plant say to water it with \frac{3}{4} cup of water every day. The plant has been getting 25% too much water. How much water has the plant been getting?

The pressure on a bicycle tire is 63 psi. This is 5% higher than what the manual says is the correct pressure. What is the correct pressure?

The crowd at a sporting event is estimated to be 3,000 people. The exact attendance is 2,486 people. What is the percent error?

A micrometer is an instrument that can measure lengths to the nearest micron (a micron is a millionth of a meter). Would this instrument be useful for measuring any of the following things? If so, what would the largest percent error be?

The thickness of an eyelash, which is typically about 0.1 millimeters.

The diameter of a red blood cell, which is typically about 8 microns.

The diameter of a hydrogen atom, which is about 100 picometers (a picometer is a trillionth of a meter).

14.3: Measuring in the Heat
A metal measuring tape expands when the temperature goes above 50\degree F. For every degree Fahrenheit above 50, its length increases by 0.00064%.

The temperature is 100 degrees Fahrenheit. How much longer is a 30-foot measuring tape than its correct length?

What is the percent error?