## Engage NY Eureka Math 3rd Grade Module 2 Lesson 21 Answer Key

Question 1.

Weigh the bags of beans and rice on the scale. Then, write the weight on the scales below.

a. Estimate, and then find the total weight of the beans and rice.

Estimate:________ + ________ ≈ ________ + ________ = _________

Actual: ________ + ________ = _________

Answer:

Estimate: 91g+58g ≈ 90g+60g=150g

Actual:91g+58g=149g

b. Estimate, and then find the difference between the weight of the beans and rice.

Estimate: ________ – ________ ≈ ________ – ________ = _________

Actual: ________ – ________ = _________

Answer:

Estimate:91g-58g ≈ 90g-60g=30g

Actual:91g-58g=33g

c. Are your answers reasonable? Explain why.

Answer:

My answers are reasonable because 150g is only 1 more than 149g and 30g is only 3 less than 33g.

Question 2.

Measure the lengths of the three pieces of yarn.

a. Estimate the total length of Yarn A and Yarn C. Then, find the actual total length.

Yarn A |
64 cm ≈ 60 cm |

Yarn B |
88 cm ≈ 90 cm |

Yarn C |
38 cm ≈ 40 cm |

Estimate:60cm+40cm=100cm

The estimated total is 100cm and the actual total is 102cm.

b. Subtract to estimate the difference between the total length of Yarns A and C, and the length of Yarn B. Then, find the actual difference. Model the problem with a tape diagram.

Answer:

Estimate:

100cm-90cm=10cm

Actual:102cm-88cm=14cm

Yarn A+Yarn C=102cm, Yarn B=88cm

Difference between the total length of Yarns A and C, and the length of Yarn B is 102-88=14cm.

Question 3.

Plot the amount of liquid in the three containers on the number lines below. Then, round to the nearest 10 milliliters.

Answer:

a. Estimate the total amount of liquid in three containers. Then, find the actual amount.

Answer:

Estimate:210+240+200=650ml

The estimated total 650ml and the actual total is 645ml.

b. Estimate to find the difference between the amount of water in Containers D and E. Then, find the actual difference. Model the problem with a tape diagram.

Answer:

The estimated difference is 30ml and the actual difference is 26ml.

Question 4.

Shane watches a movie in the theater that is 115 minutes long, including the trailers. The chart to the right shows the length in minutes of each trailer.

a. Find the total number of minutes for all 5 trailers.

Answer:

The total is 5+4+3+5+4=21 minutes

b. Estimate to find the length of the movie without trailers. Then, find the actual length of the movie by calculating the difference between 115 minutes and the total minutes of trailers.

Trailer | Length in minutes |

1 | 5 minutes |

2 | 4 minutes |

3 | 3 minutes |

4 | 5 minutes |

5 | 4 minutes |

Total |

Answer:

115min – 21 min 120-20=100min

115min-21min=94min

The estimated length is 100 minutes and the actual length is 94minutes.

c. Is your answer reasonable? Explain why.

Answer:

Yes, it is reasonable because 94minutes is close to 100minutes.

### Eureka Math Grade 3 Module 2 Lesson 21 Exit Ticket Answer Key

Rogelio drinks water at every meal. At breakfast, he drinks 237 milliliters. At lunch, he drinks 300 milliliters. At dinner, he drinks 177 milliliters.

a. Estimate the total amount of water Rogelio drinks. Then, find the actual amount of water he drinks at all three meals.

Answer:

Estimate:

237 ml ≈ 200 ml

300 ml ≈ 300 ml

177 ml ≈ 177 ml

200+300+177=677ml

About 677ml amount of water Rogelio drinks

Actual:

237+300+177ml=714 ml

Therefore, the actual amount of water he drinks at all three meals is 714.

b. Estimate how much more water Rogelio drinks at lunch than at dinner. Then, find how much more water Rogelio actually drinks at lunch than at dinner.

Answer:

Estimate:

300 ml ≈ 300 ml

177 ml ≈ 200 ml

300-200=100 ml

About 100ml more water Rogelio drinks at lunch than at dinner

Actual:

300 ml- 177 ml=123ml.

123 ml of water Rogelio actually drinks at lunch than at dinner

### Eureka Math Grade 3 Module 2 Lesson 21 Homework Answer Key

Question 1.

There are 153 milliliters of juice in 1 carton. A three-pack of juice boxes contains a total of 459 milliliters. Estimate, and then find the actual total amount of juice in 1 carton and in a three-pack of juice boxes.

153 mL + 459 mL ≈ ______ + ______ =______

153 mL + 459 mL = ______

Answer:

153 ml + 459 ml ≈ 200 ml + 500 ml=700ml

153 ml + 459 ml =612 ml

b. Estimate, and then find the actual difference between the amount in 1 carton and in a three-pack of juice boxes.

459 mL − 153 mL ≈ ______ − ______ = ______

459 mL − 153 mL = ______

Answer:

459 ml – 153 ml ≈ 500 ml – 200 ml=300ml

459 ml – 153 ml = 306 ml

c. Are your answers reasonable? Why?

Answer:

No, my answer in addition is not reasonable as it is not close to the actual answer.

Yes, my answers in subtraction is reasonable as it is close to the actual answer.

Question 2.

Mr. Williams owns a gas station. He sells 367 liters of gas in the morning, 300 liters of gas in the afternoon, and 219 liters of gas in the evening.

a. Estimate, and then find the actual total amount of gas he sells in one day.

Answer:

Estimate:

367 L + 300 L + 219 L ≈ 400 L + 300 L + 200 L = 900 L

The estimated total amount of gas Mr.Williams sells in one day is 900L.

Actual:

367 L + 300 L + 219 L =886 L

The actual total amount of gas Mr.Williams sells in one day is 886 L.

b. Estimate, and then find the actual difference between the amount of gas Mr. Williams sells in the morning and the amount he sells in the evening.

Answer:

367 L – 219 L ≈ 400 L – 200 L = 200 L

The estimated difference between the amount of gas Mr. Williams sells in the morning and the amount he sells in the evening

Actual:

367 L – 219 L = 148 L

The actual difference between the amount of gas Mr. Williams sells in the morning and the amount he sells in the evening

Question 3.

The Blue Team runs a relay. The chart shows the time, in minutes, that each team member spends running.

a. How many minutes does it take the Blue Team to run the relay?

Blue Team |
Time in Minutes |

Jen |
5 minutes |

Kristin |
7 minutes |

Lester |
6 minutes |

Evy |
8 minutes |

Total |
26 minutes |

Answer:

The Blue Team took 28 minutes to run the relay.

b. It takes the Red Team 37 minutes to run the relay. Estimate, and then find the actual difference in time between the two teams.

Answer:

Estimate:

37 min ≈ 40 min

26 min ≈ 30min

40-30=10min

The estimated difference in time between the two teams is 10 minutes

Actual:

37 min – 26 min=11 min

The actual difference in time between the two teams is 11 minutes.

Question 4.

The lengths of three banners are shown to the right.

a. Estimate, and then find the actual total length of Banner A and Banner C.

Banner A |
437 cm |

Banner B |
457 cm |

Banner C |
332 cm |

Answer:

Estimate:

437 cm + 332 cm ≈ 400 L + 300 L =700 L

The estimate total length of Banner A and Banner C = 700 cm.

Actual:

437 cm + 332 cm = 769 cm

The actual total length of Banner A and Banner C = 769 cm.

b. Estimate, and then find the actual difference in length between Banner B and the combined length of Banner A and Banner C. Model the problem with a tape diagram.

Answer:

Estimate:

(437 cm+332 cm) – 457 L ≈ (400+300cm) – 400 L = 700 cm – 400 L =300 L

The estimated difference in length between Banner B and the combined length of Banner A and Banner C is 300 cm

Actual:

(437 cm+332 cm) – 457 L = 769 cm – 457 cm = 312 cm.

The actual difference in length between Banner B and the combined length of Banner A and Banner C is 312 cm