A middle school surveyed 260 students about how they travel to school, and 35% said they walk or ride a bike. How many of the surveyed students walk or ride a bike?
A7✗ Incorrect
Incorrect. This answer divides the whole by the percent.
B91✓ Correct
Correct. 35% of 260 = 35 ÷ 100 × 260 = 91.
C169✗ Incorrect
Incorrect. This answer finds the remaining part instead of the percent asked for.
D9,100✗ Incorrect
Incorrect. This answer forgets to divide the percent by 100.
Answer
B. 91
Rationale
A percent counts parts out of 100, so 35% is first rewritten as a decimal by dividing 35 by 100. Multiplying that decimal by the 260 students surveyed gives the size of the group that walks or bikes. Because the percent is under 100, the answer must be smaller than 260, which is a quick way to catch a slip.
Worked solution: 35% of 260 = 35 ÷ 100 × 260 = 91.
RememberTo find a percent of a number, divide the percent by 100, then multiply by the whole.
Sources
DOE-HDBK-1014/1-92U.S. Department of Energy · License: US government work (public domain) · Retrieved · Page 77
NIST Special Publication 330National Institute of Standards and Technology · License: US government work (public domain) · Retrieved · Page 50
Guide for theNational Institute of Standards and Technology · License: US government work (public domain) · Retrieved · Page 31
Lesson 3: Measures of Risk (Source: CDC)Centers for Disease Control and Prevention (CDC) · License: CDC content (credit required) · Retrieved · Properties and uses of proportions
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