Resources

Resources

Add and subtract integers: word problems

Read this word problem.

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A dolphin was swimming

7

meters below the surface of the ocean. It located a squid and dove down

4

more meters to eat it. What is the location of the dolphin now relative to the surface?

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To solve the problem, Lamar subtracted

-7 - (-4)

and came up with an answer of

-3

meters. Is Lamar correct? Why or why not?

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(A) Yes, Lamar is correct.

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(B) No. The answer should have been

11

-3

meters, because the sum of the absolute values of the numbers is

11

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(C) No. Lamar should have subtracted

-7 - 4

because the dolphin started

7

meters below the surface and dove down

4

Read this word problem.

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A guppy was swimming

8

feet below the surface of the river. It swam down

6

more feet to escape a large, hungry fish. What is the position of the guppy now relative to the surface?

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To solve the problem, Jenna subtracted

8 - 6

and came up with an answer of

2

feet. Is Jenna correct? Why or why not?

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(A)Yes, Jenna is correct.

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(B)No. The answer should have been

-2

2

feet, because the guppy is below the surface.

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(C)No. Jenna should have subtracted

-8 - 6

because the guppy started

8

feet below the surface and swam down

6

Read this word problem.

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Lake Eyre, which has the lowest elevation in Australia, is

16

meters below sea level. The Taieri Plain, the lowest place in New Zealand, is

2

meters below sea level. How much higher is the Taieri Plain than Lake Eyre?

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To solve the problem, Elise subtracted

-2 - (-16)

and came up with an answer of

-18

meters. Is Elise correct? Why or why not?

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(A) Yes, Elise is correct.

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(B) No. The answer should have been

14

-18

meters, because subtracting a negative number is the same as adding its opposite.

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(C) No. Elise should have added

-2 + (-16)

because the Taieri Plain is higher.

Michael measured the same table two times. The table was

4

feet tall the first time and approximately

1

2

meters tall the second time. Determine which explanation below is the best reason on why the measurements are not the same.

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A Feet are shorter than meters, therefore more feet are used.

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B Feet are longer than meters, therefore there are more feet.

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C Meters are longer than feet, therefore more meters are used.

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D Meters are shorter than feet, therefore more meters are used.

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E I don't know yet

Leo is going to use a random number generator

400

times. Each time he uses it, he will get a

1,2,3,4

5

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What is the best prediction for the number of times that Leo will get an odd number?

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1

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133

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133

times but probably not exactly

133

Twenty cards are numbered

1-20

. You draw a card. Without replacing it, you draw a second card. Find the probability that the first card will be an even number and the second card drawn will be an even number.

The train from Station A to Station B leaves at

7

24

a.m. The trip usually takes

34

minutes Today, the train is

4

minutes late. Will the train arrive at Station B before

8

00

8

00

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How do you know?

From midnight to

2: 00

\mathrm{am}

, the temperature dropped

1.2^{\circ} \mathrm{C}

each hour. If the temperature at midnight was

-10^{\circ} \mathrm{C}

, what was the temperature at

2

00

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\square

{ }^{\circ} \mathrm{C}

Allison spends a winter day recording the temperature once every three hours for science class. At

9 \mathrm{am}

, the temperature was

-13^{\circ} \mathrm{F}

9 \mathrm{am}

and noon, the temperature increased by

14 \cdot 1^{\circ} \mathrm{F}

. Between noon and

3 \mathrm{pm}

, the temperature went down

1.1^{\circ} \mathrm{F}

3 \mathrm{pm}

6 \mathrm{pm}

, the temperature went down

9.1^{\circ} \mathrm{F}

. What was the temperature at

6 \mathrm{pm}

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\square

^{\circ} \mathrm{F}