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Problems involving Percent Up
Let's recall the definition of Percent
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A.
a) Working with the problems involving percent,
convert it to the number,
moving
the decimal point for 2 places to the left.
b) If you are asked to find the percent of a number, multiply converted
percent by the given
number.
Example 1
Find 600% of .075
Step 1
600 % = 6
Step 2 
B. It
is helpful to use a proportion to solve the problems involving
percent.
Example 2
Mike had 14 correct answers on his test
out of 25 total questions.
What percent did he get correct ?
Step 1
Use the proportion.
Step 2
Cross-multiply to solve for X
Example 3
In a class of 20 boys and 28 girls what percent of the
class are girls ?
Step 1
a) Underline the question
b) Identify
what you have to find : What percent are girls out of the total number
of students in class ?
c) What is
the total number of students in class ?
Number of girls + Number of boys = 20 + 28 = 48 students
Step 2
Use the proportion
Step 3
Solve the proportion by cross-multiplying
Example 4
In a class of 550 students, 42 percent wish to go to college. How many students
wish to go to college ?
Step 1
Proportion
Step 2
Solve for x by cross-multiplying
x = 231 ( students wish to attend college )
Example 5
Step 1
What average must a student earn in her seventh semester in order
to attain a
scholastic average of 80 percent if her averages for her previous
semesters were as
follows: semester I - 71%, semester II - 75%, semester III
and semester IV - 80%, semester
V - 86%, and semester VI - 88% ?
A) 80%; B)
82%; C) 83%; D) 84%; E) 85%
tip 
Make a chart with info given
|
Semester # |
Sem I | Sem II | Sem III | Sem IV | Sem V | Sem VI | Sem VII |
|
Average score |
71% | 75% | 80% | 80% | 86% | 88% | x |
Step 2
Use the definition of average
Step 3
Find the sum of averages ( multiply both sides by 7 )
Step 4
Solve for x
Answer is "A"
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