4.3 · Part II
Supported Application · Guided Entry to Today's Problem
estimate · benchmark percent
- Use benchmark percents: 10% (move decimal left 1), 1% (move left 2), 50% (half), 25% (quarter)
- Combine benchmarks (e.g. 15% = 10% + 5%; 75% = 50% + 25%)
- Round numbers to compatible values for quick mental estimates
- estimate (estimación) — A reasoned answer that is close enough to be useful, found without exact computation.
- benchmark percent (porcentaje de referencia) — A friendly percent — 1%, 10%, 25%, 50%, 75%, 100% — used as a landmark for estimating.
- compatible numbers (números compatibles) — Numbers close to the originals that are easy to compute with mentally.
- double number line (recta numérica doble) — Two parallel number lines that pair amounts with their percents at the same positions.
- the whole (el todo) — The quantity that counts as 100% in a problem — and it can change between questions.
- Keeping the same whole for every question — when the problem says 'of the used storage,' the whole changes from 6 GB to 4 GB, and estimates anchored to the old whole are wrong before any arithmetic happens.
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1 MULTIPLE CHOICE
To estimate 8.6% of 216 by rounding, which numbers should you use?
- A10% of 220
- B8% of 300
- C86% of 216
- D1% of 216
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
What is 10% of 220?
- A22
- B2.2
- C220
- D44
Work- 1Whole100% is what number?
- 2Find 10%Divide by 10.
- 3BuildAdd or multiply to the percent.
- 4CheckIs it under or over the whole?
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3 OPEN RESPONSE
The word 'approximately' appears in the storage problem. What does it tell you about the answer you need?
💬 Sentence Starter: 'Approximately' tells me ___ .<br>So instead of computing exactly, I can ___ .✏️ Mathematical Justification & Response
Writing Task: Justify why your mathematical solution is accurate and complete.
4.3 · Part II
On-Level Application · Standard Rigor
estimate · benchmark percent
- Use benchmark percents: 10% (move decimal left 1), 1% (move left 2), 50% (half), 25% (quarter)
- Combine benchmarks (e.g. 15% = 10% + 5%; 75% = 50% + 25%)
- Round numbers to compatible values for quick mental estimates
- estimate (estimación) — A reasoned answer that is close enough to be useful, found without exact computation.
- benchmark percent (porcentaje de referencia) — A friendly percent — 1%, 10%, 25%, 50%, 75%, 100% — used as a landmark for estimating.
- compatible numbers (números compatibles) — Numbers close to the originals that are easy to compute with mentally.
- double number line (recta numérica doble) — Two parallel number lines that pair amounts with their percents at the same positions.
- the whole (el todo) — The quantity that counts as 100% in a problem — and it can change between questions.
- Keeping the same whole for every question — when the problem says 'of the used storage,' the whole changes from 6 GB to 4 GB, and estimates anchored to the old whole are wrong before any arithmetic happens.
-
1 MULTIPLE CHOICE
The Green-Team recycled 216 pounds; 8.6% was metal. Using compatible numbers 10% and 200, the estimate is:
- A20 pounds
- B2 pounds
- C208 pounds
- D86 pounds
Work -
2 MULTIPLE CHOICE
Photos use 3.5 GB of the 4 GB of used storage. About what percent of the USED storage is photos?
- AAbout 87%
- BAbout 58%
- CAbout 35%
- DAbout 99%
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
Why did the whole change between the two storage questions?
- AThe second question asks about the used storage, so 4 GB becomes 100%
- BThe phone gained storage between the questions
- CThe whole never changes in a percent problem
- DBecause photos are more important than mail
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.
4.3 · Part II
Extension & Non-Routine Application
estimate · benchmark percent
- Use benchmark percents: 10% (move decimal left 1), 1% (move left 2), 50% (half), 25% (quarter)
- Combine benchmarks (e.g. 15% = 10% + 5%; 75% = 50% + 25%)
- Round numbers to compatible values for quick mental estimates
- estimate (estimación) — A reasoned answer that is close enough to be useful, found without exact computation.
- benchmark percent (porcentaje de referencia) — A friendly percent — 1%, 10%, 25%, 50%, 75%, 100% — used as a landmark for estimating.
- compatible numbers (números compatibles) — Numbers close to the originals that are easy to compute with mentally.
- double number line (recta numérica doble) — Two parallel number lines that pair amounts with their percents at the same positions.
- the whole (el todo) — The quantity that counts as 100% in a problem — and it can change between questions.
- Keeping the same whole for every question — when the problem says 'of the used storage,' the whole changes from 6 GB to 4 GB, and estimates anchored to the old whole are wrong before any arithmetic happens.
-
1 MULTIPLE CHOICE
A jacket originally priced at $78.99 is on sale for 25% off. Which is the best estimate of the discount amount?
- A$20
- B$10
- C$40
- D$8
✏️ Workspace & Solution Steps -
2 MULTIPLE CHOICE
Two students estimate 8.6% of 216. Ana uses 10% of 220 = 22. Ben uses 10% of 200 = 20. Whose estimate is closer to the exact answer, 18.576?
- ABen's — 20 is 1.4 away; Ana's 22 is 3.4 away
- BAna's — 22 is closer to 18.576
- CThey are equally close
- DNeither is a valid estimate
✏️ Workspace & Solution Steps -
3 MULTIPLE CHOICE
For which problem is ESTIMATING clearly the right tool, rather than exact computation?
- ADeciding if a $58 jacket at 25% off fits your $45 budget
- BProgramming a bank to compute interest on every account
- CReporting a medicine dose
- DScoring a state test
✏️ Workspace & Solution Steps
Writing Task: Justify why your mathematical solution is accurate and complete.