Math 65 Enrichment Answers and Notes

[ Return to Math 65 Enrichment Problems ]


1i) a.

1g) Answers will vary: ones', tens', or hundreds' place.

1f) Answers will vary.


2i) a.

2g) Answers will vary.

2f) Answers will vary.


3i)

 

0

1

2

3

4

5

6

7

8

9

10

11

12

0

0 0 0 0 0 0 0 0 0 0 0 0 0

 1

0 1 2 3 4 5 6 7 8 9 10 11 12

2

0 2 4 6 8 10 12 14 16 18 20 22 24

3

 0 3 6 9 12 15 18 21 24 27 30 33 36

4

0 4 8 12 16 20 24 28 32 36 40 44 48

5

0 5 10 15 20 25 30 35 40 45 50 55 60

6

0 6 12 18 24 30 36 42 48 54 60 66 72

7

0 7 14 21 28 35 42 49 56 63 70 77 84

8

0 8 16 24 32 40 48 56 64 72 80 88 96

9

0 9 18 27 36 45 54 63 72 81 90 99 108

10

0 10 30 30 40 50 60 70 80 90 100 110 120

11

0 11 22 33 44 55 66 77 88 99 110 121 132

12

0 12 24 36 48 60 72 84 96 108 120 132 144

3g)

  1. b.
  2. c.
  3. a.

3f) Some patterns are:


4i) b.

4g) a.

4f)

128 ounces ÷ 4 = 32 ounces in a quart
32 ounces ÷ 2 = 16 ounces in a pint
16 ounces ÷ 2 = 8 ounces in a cup

5i)

  1. a.
  2. c.
  3. b.

5g)

  1. 24 x 800 = 24 x 20 x 40 = 480 x 40 = 19,200
  2. 32 x 1200 = 32 x 30 x 40 = 960 x 40 = 38,400
  3. 15 x 1500 = 15 x 30 x 50 = 450 x 50 = 22,500

5f)

  1. 30 days x 20 miles per day = 600 miles
  2. 80 days x 20 miles per day = 3600 miles
  3. 365 days x 20 miles per day = 7300 miles

6i)

  1. b.
  2. a.
  3. c.
  4. b.
  5. a.
  6. c.
  7. b.

6g) Answers will vary. Students may not be able to do all of them.

6f)

  1. 1/2 + 2/5 = 50% + 40% = 90%
  2. 1/4 + 1/2 = 25% + 50% = 75%
  3. 3/5 + 1/2 = 60% + 50% = 110%

7i)

  1. b.
  2. a.

7g)

  1. c.
  2. a.
  3. b.

7f) Answers will vary.


8i) a.

8g) Answers will vary depending on the number of students in the class.

8f) Answers will vary depending on the number and ages of people in your family.


9i)

  1. b.
  2. a.

9g)

  1. ten thousands' and tens'
  2. one hundred millions' and one hundred thousands'
  3. millions' and tens'

9f)
 Number

 Number in Words

 10  ten
 100  one hundred
 1,000  one thousand
 10,000  ten thousand
 100,000  one hundred thousand
 1,000,000  one million
 10,000,000  ten million
 100,000,000  one hundred million


10i)

  1. b.
  2. a.

10g)

Estimate: 1) 20 X 40 = 800; 2) 10 X 50 = 500; 3) 40 X 30 = 1200
Actual: 1) 24 X 36 = 864; 2) 12 X 48 = 576; 3) 42 X 29 = 1218

10f) Answers will vary. The estimates should be within about 100.


11i)

  1. c.
  2. a.
  3. a.

11g) Answers will vary.

11f) Answers will vary. If your child has difficulty or incorrect answers, have him or her refer to the textbook and review the process with your child.


12i)

  1. a.
  2. c.

12g)

  1. a.
  2. c.
  3. a.

12f) Answers will vary.


13i)

  1. c.
  2. a.
  3. b.

13g)

  1. 72 ÷ 3 = 24; so multiply by 24/24
  2. 80 ÷ 5 = 16, and 16/16 = 1; so 16/80 = 1/5
  3. 72 ÷ 5 = 12; so multiply by 12/12
    (1) + (3) = 48/72 + 12/72 = 60/72 or 5/6

13f) 1/2, 2/4, 3/6; 4/5, 8/10, 12/15; 2/3, 4/6, 6/9

To write an equivalent fraction, multiply both parts by the same number. For example, 1/2 X 2/2 = 2/4.


14i)

  1. b.
  2. a.

14g)

1024 ÷ 2 = 512
512 ÷ 2 = 256
256 ÷ 2 = 128
128 ÷ 2 = 64
64 ÷ 2 = 32
32 ÷ 2 = 16
16 ÷ 2 = 8
8 ÷ 2 = 4
4 ÷ 2 = 2
2 ÷ 2 = 1

Ten people got to answer a question.

729 ÷ 3 = 243
243 ÷ 3 = 81
81 ÷ 3 = 27
27 ÷ 3 = 9 9 ( 3 = 3
3 ÷ 3 = 1

Six people got to answer a question.

1024 ÷ 4 = 256
256 ÷ 4 = 64
64 ÷ 4 = 16
16 ÷ 4 = 4
4 ÷ 4 = 1

Five people got to answer a question.

14f)

  1. 3/4 ( 12/1 = 36/4 = 9 months
  2. 5/6 ( 24/1 = 120/6 = 20 months
  3. 3/7 ( 21/1 = 63/7 = 9 days

15i) b.

15g) Answers will vary.

15f) Answers will vary, depending on mileage.


16i)

  1. c.
  2. b.

16g) Answers will vary.

16f) Answers will vary.


17i) a.

17g) Answers will vary.

17f) Answers will vary.


18i) b.

18g) The combinations are:
1 foot by 24 feet 2 feet by 12 feet 3 feet by 8 feet 4 feet by 6 feet

18f) Answers will vary, depending on the size of your home.


19i)

  1. a.
  2. b.
  3. b.
  4. c.

19g)

  1. 12 5/8 + 53 1/4 = 12 5/8 + 53 2/8 = 65 7/8
  2. 2 1/3 + 5 1/6 = 2 2/6 + 5 1/6 = 7 3/6, or 7 1/2
  3. 7 3/4 - 2 1/2 = 7 3/4 - 2 2/4 = 5 1/4
  4. 84 13/16 - 36 3/8 = 84 13/16 - 36 6/16 = 48 7/16

19f)

1 1/3 cups + 1 1/4 cups +2/3 cup + 1/2 cup + 1/4 cup
= 1 4/12 cups + 1 3/12 cups + 8/12 cup + 6/12 cup + 3/12 cup
= 2 24/12 cups = 4 cups
4 cups = 2 pints
2 pints = 1 quart

20i)

  1. a.
  2. c.

20g)

1/2 X 2 1/2 groups = 1/2 X 5/2 groups = 5/4 group = 1 1/4 group = 5 students
1/3 X 1 1/2 groups = 1/3 X 3/2 groups = 3/6 group = 1/2 group = 2 students

20f) Answers will vary. The actual area and the rounded area should be fairly close.