Addition
Subtraction
Probability
Story Problems
What's the Error?
100

-8+13

5

100

-6-9

-15

100

You flip a coin and roll a six-sided number cube. What is the probability of getting heads and a 5?

1/12

100

A diver is 18.4 ft below sea level. She rises 7.9 ft. What is her new elevation?

-10.5 ft

100

A student says 7+(−12)=5. What did they do wrong?

Answer: -5, -12 has the greater absolute value so it needs to be a negative 5

200

-3/4+5/8

-1/8

200

6.5-9.2

-2.7

200

A restaurant lets you choose from 3 entrées, 4 sides, and 2 drinks. How many different meals can you create by choosing one of each?

24 different meals

200

A hiker begins at an elevation of 6,250.5 ft. She climbs 825.75 ft and then descends 1,040.25 ft. What is her final elevation?

6,036 ft

200

A student says −4.5−3.2=−1.3. What did they do wrong?

Answer: −7.7 They treated subtraction like finding the difference of the absolute values.

300

-6.75+(-2.8)+9.4

-0.15

300

-2/3-5/6

-1 1/2

300

A bag contains 5 red and 3 blue marbles. You choose one marble without replacing it, then choose another. What is the probability of choosing two blue marbles?

3/8*2/7=3/28

300

The temperature was -4.5 degrees F in the morning. It increased 7.8 degree then decreased 5.6 degrees. What was the final temperature? 

-2.3 degree F

300

A student solves the following below, find and correct the error. 

-3/4+5/8=-2/8


They didn't find a common denominator. Answer = 

-1/8

400

-3 1/4+5 5/6

2 7/12

400

-2 1/3 - (-1 5/6)

-1/2

400

There are 7 boys and 5 girls in a group. Two students are randomly selected without replacement. What is the probability that both are girls?

5/12 * 4/11 = 5/33

400

Jordan owes a friend $18.50. Jordan earns $45.75, pays back the $18.50, and then spends $32.40. What is Jordan's final amount?

-$5.15

400

A student says that... What mistake did they make? 

2 1/4-(-3 1/2)=-1 1/4

Subtracting a negative becomes addition. Answer:

5 3/4

500

-3 1/4+2.75-(-1 2/3)

1 1/6

500

4 2/5-(-2.75)+(-3 3/10)

3.85

500

Three cards are drawn without replacement. What is the probability that all three are face cards?

12/52*11/51*10/50=11/1105

500

At noon, a submarine was at −184.6 ft. At 1 P.M., it was at −257.9 ft. What was the change in its elevation?

-73.3 ft

500

Find the error and give the correct answer:

-2.6-(-1 3/4)+5/8=-4.975

They forgot that subtracting a negative becomes addition. Answer: 

-0.225