556 Chapter 6 Percent
3 Estimate answers to percent problems involving 200%.
Since 100% of a number is the number itself, it follows that 200% of a number would
be twice the number. We can extend this rule to quickly find multiples of 100% of a
number.Finding 200%, 300%, 400%,...of a NumberTo find 200% of a number, multiply the number by 2. A similar approach can
be used to find 300% of a number, 400% of a number, and so on.EXAMPLE (^8) Estimate the answer: What is 200% of 5.673?
StrategyWe will multiply an approximation of 5.673 by 2.
WHYTo find 200% of a number, multiply the number by 2.
SolutionTo estimate 200% of 5.673, we will find 200% of 6. We use 6 as an
approximation because it is close to 5.673 and it makes the multiplication by 2 easy.
200% of 5.673 12 Because 200% of 6 2 6 12.
Self Check 8
Estimate the answer: What is
200% of 12.437?
Now TryProblem 43
4 Use estimation to solve percent application problems.
In the previous examples of this section, we were given the percent (1%, 10%, 50%,
25%, 5%, 15%, or 200%), we approximated the base, and then we estimated the
amount. Sometimes we must approximate the percent, as well, to estimate an answer.
EXAMPLE (^9) Music Education Of the 350 children attending an
elementary school, 24% of them are enrolled in the instrumental music program.
Estimate the number of children taking instrumental music.
StrategyWe will use the rule from this section for finding 25% of a number.
WHY24% is approximately 25%, and there is a quick way to find 25% of a
number.
Solution24% of the 350 children in the school are taking instrumental music. To
estimate 24% of 350, we will find 25% of 360. We use 360 as an approximation
because it is close to 350 and it is divisible by 4.
Because 25% of.
There are approximately 90 children in the school taking instrumental music.
24% of 350 90 360 ^3604 90
Self Check 9
STUDENT DRIVERSOf the 1,550
students attending a high school,
26% of them drive to school.
Estimate the number of students
that drive to school.
Now TryProblem 85
1.5.193, 5 2.353.6 lb, 400 lb 3. 26 4.7,000,000 5. 7 6.1,210 7.$4.50
- 24 9.400 students
ANSWERS TO SELF CHECKS