Rounding Estimation and Approximation
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Rounding Estimation and Approximation — Free MYP3 Mathematics Practice Questions

1QuestionEstimating Products and QuotientsConcept Practice
2 marks~3 minCriterion A
A rectangle has side lengths of 4.84.8 cm and 6.26.2 cm.

(a) Round each side length to the nearest whole number and calculate the estimated area of the rectangle using

Area=length×width.\text{Area} = \text{length} \times \text{width.}

Give your answer in cm². [2]
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Solutions

2QuestionEstimating Products and QuotientsAssessment Practice
4 marks~6 minCriterion D
A student estimates the cost of 48 concert tickets, each priced at 35 dollars, by rounding 48 up to 50 and calculating 50×35=175050 \times 35 = 1750 dollars. The actual cost is 48×35=168048 \times 35 = 1680 dollars.
a
Justify whether 1750 dollars is a valid estimate, and explain why it is an overestimate. [2]
b
Describe a real-world situation in which using this overestimate could cause a problem, and explain how the problem arises. [2]
Question diagram

Solutions

3QuestionEstimating Sums and DifferencesConcept Practice
2 marks~3 minCriterion B
Each addition problem below has been rounded to the nearest ten to produce an estimated sum.

47+3247 + 32exact sum 7979estimated sum 8080
51+2951 + 29exact sum 8080estimated sum 8080
48+3348 + 33exact sum 8181estimated sum 8080
46+3146 + 31exact sum 7777estimated sum 8080


Compare the estimated sum to the exact sum in each problem. [1]

Explain why the estimated sum is sometimes higher, sometimes lower, and sometimes equal to the exact sum. [1]

Solutions

4QuestionRounding Decimals to Given PlacesAssessment Practice
5 marks~8 minCriterion C
A student claims that 0.4490.449 rounded to one decimal place is 0.50.5, arguing it is closer to 0.50.5 than to 0.40.4.
a
State the correct value of 0.4490.449 rounded to one decimal place and identify the digit that determines this. [1]
b
Using a number line from 0.40.4 to 0.50.5, mark the positions of 0.440.44, 0.450.45, and 0.4490.449. Explain why 0.4490.449 rounds to your answer from part (a). [2]
c
The student's reasoning contains a flaw. Justify why the student's argument is incorrect, using distance calculations to support your answer. [2]
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Solutions

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