Answer Keys: Percent Concepts

Student Concept Worksheet Answers

1

a) 35% | b) 80% | c) 5%

Move decimal right 2 places: 0.35 = 35%, 0.8 = 80%, 0.05 = 5%

2

a) 0.60 | b) 0.05 | c) 1.25

Move decimal left 2 places: 60% = 0.60, 5% = 0.05, 125% = 1.25

3

a) 25% | b) 60% | c) 70%

1/4 = 0.25 = 25%, 3/5 = 0.6 = 60%, 7/10 = 0.7 = 70%

4

a) 60 | b) 20 | c) 4.5

50% of 120 = 0.5 x 120 = 60. 25% of 80 = 0.25 x 80 = 20. 10% of 45 = 0.1 x 45 = 4.5

5

$12 discount

20% of $60 = 0.20 x 60 = $12

Practice Worksheet Answers

Part A: Decimal to Percent

#	Decimal	Percent	Work
1	0.45	45%	Move decimal right 2
2	0.7	70%	0.70 = 70%
3	0.08	8%	Move decimal right 2
4	0.125	12.5%	Move decimal right 2
5	1.5	150%	Move decimal right 2
6	0.005	0.5%	Move decimal right 2

Part B: Percent to Decimal

#	Percent	Decimal	Work
7	65%	0.65	Move decimal left 2
8	8%	0.08	Move decimal left 2
9	120%	1.20	Move decimal left 2
10	2.5%	0.025	Move decimal left 2
11	33%	0.33	Move decimal left 2
12	100%	1.00	Move decimal left 2

Part C: Fraction to Percent

#	Fraction	Percent	Work
13	1/2	50%	1/2 = 0.5 = 50%
14	3/4	75%	3/4 = 0.75 = 75%
15	2/5	40%	2/5 = 0.4 = 40%
16	7/10	70%	7/10 = 0.7 = 70%
17	1/8	12.5%	1/8 = 0.125 = 12.5%
18	5/8	62.5%	5/8 = 0.625 = 62.5%

Part D: Find Percent of a Number

#	Problem	Answer	Work
19	50% of 80	40	0.5 x 80 = 40
20	25% of 60	15	0.25 x 60 = 15
21	10% of 250	25	0.1 x 250 = 25
22	75% of 120	90	0.75 x 120 = 90
23	15% of 80	12	0.15 x 80 = 12
24	40% of 150	60	0.4 x 150 = 60

Part E: Word Problems

25

$24 discount

30% of $80 = 0.30 x 80 = $24

26

51 questions

85% of 60 = 0.85 x 60 = 51 questions correct

27

$9 tip

20% of $45 = 0.20 x 45 = $9

28

$59.50 sale price

15% of $70 = 0.15 x 70 = $10.50 discount. Sale price = $70 - $10.50 = $59.50

29

84 students

35% of 240 = 0.35 x 240 = 84 students

Challenge Questions:

#30: First discount: 25% of $40 = $10, so sale price = $30. Second discount: 20% of $30 = $6. Final price = $30 - $6 = $24

#31: Option A: 30% of $50 = $15 off, pay $35. Option B: 20% of $60 = $12 off, pay $48. 30% off $50 is the better deal (you pay $35 instead of $48).

FAST Practice Quiz Answers

1

C) 35%

0.35 x 100 = 35% (move decimal right 2 places). A is common error of not moving. B moved only 1 place.

2

C) 60%

3/5 = 3 divided by 5 = 0.6 = 60%. A (35%) confuses digits. B (53%) reverses division.

3

A) 21

25% = 0.25. 0.25 x 84 = 21. Or: 25% = 1/4, so 84/4 = 21.

4

Select: 0.75, 3/4, and 15/20

0.75 = 75% (move decimal right 2)
3/4 = 0.75 = 75%
0.075 = 7.5% (NOT 75%)
15/20 = 15/20 = 0.75 = 75%
7.5 = 750% (NOT 75%)

5

A) $9

15% of $60 = 0.15 x 60 = $9 discount. C and D are the sale price, not the discount.

6

C) 24 students

60% of 40 = 0.60 x 40 = 24 students. A confuses 60 and 6. B subtracts instead of multiplies.

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