Proportions and Percentages - GED Math
Card 1 of 430
What is 25% of 240?
What is 25% of 240?
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To find a percentage of a whole number, we will multiply the two together. So, we get
Now, the zero in 100 and the zero in 240 can cancel. We get
Therefore, 25% of 240 is 60.
To find a percentage of a whole number, we will multiply the two together. So, we get
Now, the zero in 100 and the zero in 240 can cancel. We get
Therefore, 25% of 240 is 60.
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45% of what number is 9?
45% of what number is 9?
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The rate is 45% and the comparative number is 9; the unknown is the original number that 9 is 45% of. The statement is "(nine) is (forty-five percent) of (some number)", so the variable stands for a number.
The rate is 45% and the comparative number is 9; the unknown is the original number that 9 is 45% of. The statement is "(nine) is (forty-five percent) of (some number)", so the variable stands for a number.
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The ratio of students to instructors at a prestigious medical school is 25:6. The school employs 90 instructors, and there will be 240 students returning. How many new students must it limit itself to admitting in order to continue to maintain this student-instructor ratio?
The ratio of students to instructors at a prestigious medical school is 25:6. The school employs 90 instructors, and there will be 240 students returning. How many new students must it limit itself to admitting in order to continue to maintain this student-instructor ratio?
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Let 
be the maximum number of students admitted overall.
For the school to maintain a 25:6 student-teacher ratio with 90 instructors, the ratios 
and 
must be equal. Therefore, we solve the proportion statement for 
:
Since 240 spots are already filled by returning students, the medical school can admit up to 
new students.
Let
For the school to maintain a 25:6 student-teacher ratio with 90 instructors, the ratios
Since 240 spots are already filled by returning students, the medical school can admit up to
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Thomas’s current yearly salary is $44,000 per year. After an 8% raise, what will his new salary be?
Thomas’s current yearly salary is $44,000 per year. After an 8% raise, what will his new salary be?
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8% of Thomas's salary of $44,000 is
.
Add this to the original salary:
8% of Thomas's salary of $44,000 is
Add this to the original salary:
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Solve:
Solve:
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At a party, there are 7 women with blonde hair, 9 women with brown hair, and 5 women with red hair. What is the proportion of women with blonde hair?
At a party, there are 7 women with blonde hair, 9 women with brown hair, and 5 women with red hair. What is the proportion of women with blonde hair?
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A proprotion is the number of a specific event (blonde women) divided by the total number of events (total number of women).
A proprotion is the number of a specific event (blonde women) divided by the total number of events (total number of women).
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Solve:
Solve:
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A bag contains 
green marbles, 
red marbles, and 
blue marbles. What is the proportion of red marbles?
A bag contains
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The proportion is equal to the number of specific events (red marbles) divided by the total number of events (sum of all colors).
The proportion is equal to the number of specific events (red marbles) divided by the total number of events (sum of all colors).
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What is 
of 
?
What is
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What is 40% of 80% of 
?
What is 40% of 80% of
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80% of 
is 
multiplied by 
, or 
.
40% of this is 
multiplied by 
; this is
.
80% of
40% of this is
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Seven tenths of three fourths of 
is what percent of 
?
Seven tenths of three fourths of
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Seven tenths of three fourths of 
is equal to
.
of a number, converted to percent, is
.
Seven tenths of three fourths of
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Ten percent of a number is six more than 5 percent of this number. Find the number.
Ten percent of a number is six more than 5 percent of this number. Find the number.
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The key word "is" indicates equality.
Ten percent of a number: 
Six more than 5 percent of this number: 
Solve and simplify:
The key word "is" indicates equality.
Ten percent of a number:
Six more than 5 percent of this number:
Solve and simplify:
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Bob's Bargain Basement has computer tables on sale at 50% off the retail price. For the holiday, an additional 15% is deducted. If the computer table is $240, how much is the table on sale for during the holiday?
Bob's Bargain Basement has computer tables on sale at 50% off the retail price. For the holiday, an additional 15% is deducted. If the computer table is $240, how much is the table on sale for during the holiday?
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In order to calculate the amount of the purchase, you first must find the cost of the table at 50% off. This can be done by taking 
of the original cost.
This could also be done by converting the percent to a decimal and then multiplying that decimal by the original cost.
Then, the next step would be to take 15% of the $120. This is done by converting the percent to a decimal and then multiplying by $120.
15% = .15 as a decimal
This additional savings of $18.00 would then be subtracted from the $120.00.
This is the amount that will be paid after all discounts and savings.
Note: Do not add the initial savings of 50% to the additional savings of 15% to get a total savings of 65% and then work your problem from there. That is not the correct way to work this problem!
In order to calculate the amount of the purchase, you first must find the cost of the table at 50% off. This can be done by taking
This could also be done by converting the percent to a decimal and then multiplying that decimal by the original cost.
Then, the next step would be to take 15% of the $120. This is done by converting the percent to a decimal and then multiplying by $120.
15% = .15 as a decimal
This additional savings of $18.00 would then be subtracted from the $120.00.
This is the amount that will be paid after all discounts and savings.
Note: Do not add the initial savings of 50% to the additional savings of 15% to get a total savings of 65% and then work your problem from there. That is not the correct way to work this problem!
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A building that is 
casts a shadow that is 
long. At the same time, another tree casts a shadow that is 
long. How tall is that tree?
A building that is
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To solve this you would set up and solve a direct proportion:
To solve this you would set up and solve a direct proportion:
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Currently, Brian pays $865 a month for his rent. Monthly rent is due to increase by 12% starting next month. Rounded to the nearest dollar, how much will he pay then?
Currently, Brian pays $865 a month for his rent. Monthly rent is due to increase by 12% starting next month. Rounded to the nearest dollar, how much will he pay then?
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12% of $865 is
.
Add that amount to the current rent:
This rounds to $969, the correct choice.
12% of $865 is
Add that amount to the current rent:
This rounds to $969, the correct choice.
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Sherry deposits $3,000 at 6% simple interest per year. How much will she have in this account after three years, assuming she does not make any withdrawals or deposits?
Sherry deposits $3,000 at 6% simple interest per year. How much will she have in this account after three years, assuming she does not make any withdrawals or deposits?
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Use the simple interest formula
with 
:
This is the simple interest earned. Add it to the original principal:
Use the simple interest formula
with
This is the simple interest earned. Add it to the original principal:
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Greg deposits $9,000 at 7% simple interest per year. How much will he have in this account after eighteen months, assuming he does not make any withdrawals or deposits?
Greg deposits $9,000 at 7% simple interest per year. How much will he have in this account after eighteen months, assuming he does not make any withdrawals or deposits?
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Use the simple interest formula
with 
(18 months = 1.5 years):
This is the simple interest earned. Add it to the original principal:
Use the simple interest formula
with
This is the simple interest earned. Add it to the original principal:
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The ratio of students to instructors at a prestigious law school is 15:4. If the school employs 120 instructors, then how many students total must it limit itself to enrolling in order to maintain this student-instructor ratio?
The ratio of students to instructors at a prestigious law school is 15:4. If the school employs 120 instructors, then how many students total must it limit itself to enrolling in order to maintain this student-instructor ratio?
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Let 
be the maximum number of students admitted.
For the school to maintain a 15:4 student-teacher ratio with 120 instructors, the ratios 
and 
must be equal. Therefore, we solve the proportion statement for 
:
The maximum number of students it can admit is 450.
Let
For the school to maintain a 15:4 student-teacher ratio with 120 instructors, the ratios
The maximum number of students it can admit is 450.
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Which of the following statements does not follow from the statement 
?
Which of the following statements does not follow from the statement
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From 
we can conclude the following:
is true, because the cross-products of a proportion statement are true.
is true, because if two ratios are equivalent, their reciprocals are equivalent.
can be demonstrated to be true as follows:
The fourth statement is false:
, which contradicts the statement that 
.
From
The fourth statement is false:
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Which of the following statements follows from the statement 
?
Which of the following statements follows from the statement
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Two ratios are equivalent if and only if their cross-products are equal. We look for the proportion statement whose cross-products are 
and 
. Of the four choices, only 
fits this criterion, so it is the correct choice.
Two ratios are equivalent if and only if their cross-products are equal. We look for the proportion statement whose cross-products are
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