Question

family note today students explored different ways of estimating: rounding (in which all numbers are rounded to a particular place value), front - end estimation (all digits to the right of the greatest place value become zeros), and using close - but - easier numbers (numbers are rounded to a number that is close in value and easy to work with). while all methods of estimation are equally valid, some may be more helpful than others for answering specific kinds of questions. read the number stories. choose an appropriate estimation strategy. ① on the walk home from school, meg stopped at the library for 22 minutes and at her grandmother’s house for 38 minutes. she spent 17 minutes walking. she left at 3:00 and was supposed to be home by 4:00. a. did meg make it home on time? no how did you get your answer? because it is past an hour (60 mins). b. why did you choose your estimation strategy? standing up is past 60 minutes is an hour and she needs to be home by 4:00 so she is late. ② you and two friends need to make 100 tacos for a party. you have made 31 tacos. your friend chris has made 24 tacos. your friend pat thinks he needs to make at least 60 tacos to have enough for the party. a. is pat correct? no how did you get your answer? because there is ten extra tacos or so. b. why did you choose your estimation strategy? i added all them together to get 101 and subtracted the answer. practice ③ 31 + 51 = ④ 45 + 64 = ⑤ 252 + 144 =

Explanation:

Step1: Calculate total time for Meg

Add the time spent at library, grandmother's house and walking. $22 + 38+17=77$ minutes.

Step2: Analyze time - limit

She left at 3:00 and was supposed to be home by 4:00, which is a 60 - minute time - limit. Since $77>60$, she did not make it home on time.

Step3: Analyze taco - making situation

For taco - making, add the number of tacos already made. $31 + 24=55$ tacos. If Pat makes 60 tacos, the total number of tacos will be $55 + 60=115$ tacos. Since they need 100 tacos, $115>100$, so Pat is not correct.

Step4: Solve addition problems

For $31 + 51$, we add the units and tens digits: $(30 + 1)+(50 + 1)=(30+50)+(1 + 1)=80+2 = 82$.
For $45+64$, we have $(40 + 5)+(60 + 4)=(40+60)+(5 + 4)=100+9 = 109$.
For $252+144$, we add the units, tens and hundreds digits: $(200+50 + 2)+(100+40 + 4)=(200+100)+(50+40)+(2 + 4)=300+90+6 = 396$.

Answer:

1a. No
1b. Total time spent is 77 minutes which is more than 60 - minute time - limit.
2a. No
2b. Total tacos made if Pat makes 60 will be 115 which is more than 100.

1. 82
2. 109
3. 396