Mathematics for IGCSE & O level - Estimation (Section 2)
1
When is an exact calculation useful?
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(C)
When accuracy is essential.
2
If the height of a person is approximately 1.7 m, how would you estimate the height of a building?
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(B)
By comparing the building to an object of a known height.
3
If the cost of one pen is $2.73. Estimate the total cost of 12 pens by rounding to the nearest whole number.
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(B)
$33
4
What does the term 'significant figures' represent?
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(B)
The digits that contribute to the precision of a number.
5
How do you round a number to a certain number of significant figures?
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(D)
Consider the digit to its right.
6
Why is it important to understand significant figures when making estimates?
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(B)
To express the level of precision
7
Which of the following steps are necessary for rounding?
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A
B
C
8
Which of the following is an example of when estimation would be most useful?
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(C)
Calculating the cost of items
9
If rounding a number, how can you be sure the answer is correct?
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(C)
Check the rule for rounding.
10
What is an important consideration when rounding?
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(B)
The required degree of accuracy.
11
If you are estimating the volume of a box and the dimensions are 5.7 cm, 8.2 cm, and 3.1 cm, what would be the most appropriate first step?
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(C)
Round each dimension to 1 significant figure.
12
When calculating the area of a circle, the radius is measured as 5.3 cm. Estimate the area of the circle by rounding the radius to 1 significant figure.
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(D)
70 cm²
13
When rounding to a given number of significant figures, the first non-zero digit should start from...
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(A)
the left of the number
14
When should you not use estimation?
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(C)
When the accuracy of the answer is critical.
15
Which of the following is a good reason to estimate the result of a calculation?
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(B)
To provide a rough idea of what the answer should be.
16
If a store sells 12 apples at $0.79 each, what is the estimated cost?
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(A)
$10
17
If you needed to estimate the answer of the following equation, which number should you round to the nearest whole number?
(8.7 + 2.4) / 2
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(A)
8.7 and 2.4
18
If calculating the volume of a room and the measurements given are 4.5m, 3.2m and 2.1m. How should you give your answer?
คำตอบ
(B)
Give the answer to 1 or 2 significant figures
19
When finding significant figures what should you consider?
คำตอบ
(B)
The first non-zero digit.
20
Which statement best describes the concept of estimation?
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(B)
Making a rough calculation based on the values
21
Which of the following should be kept in mind when working to a sensible degree of accuracy?
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A
C
22
What is the key reason for using estimation in a real-world scenario?
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(B)
To save time and simplify the problem
23
When rounding 145 to 2 significant figures, what is the answer?
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(B)
150
24
In estimation, to estimate answers to problems, you can round each ___ to 1 significant figure and then carry out the calculation.
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(B)
number
25
What is the main benefit of estimating when doing a complex math problem?
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(B)
To simplify the process
26
Which of the following describes the best use for estimation?
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(B)
To get a quick answer.
27
When is estimating the volume of a cube when its sides are 2.5 cm best?
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(B)
When there is a need to approximate the answer quickly
28
When calculating the result of a multiplication problem by rounding to 1 significant figure, why is this method useful?
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(B)
It will provide an easy calculation
29
When finding a sensible degree of accuracy, which is correct?
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C
D
30
What is the main point of estimating the length of the truck, if a car is 3.8m long?
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(B)
To use known measures to help the estimation
31
What is the purpose of rounding numbers?
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(C)
To simplify calculations and show a level of precision.
32
What is the approximate value of 0.00987 to 2 significant figures?
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(B)
0.0098
33
What is a useful strategy when estimating the answer to a division problem?
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(B)
Round both the dividend and divisor to one significant figure, then divide.
34
What is 0.072419 rounded to 1 significant figure?
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(A)
0.07
35
If the digit to the right of the desired decimal place is 5 or greater, what do you do?
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(C)
Round the digit up by 1.
36
To how many significant figures should 12,345 be rounded to if you need the answer to be accurate to the nearest thousand?
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(B)
2
37
When rounding 6.217 to 1 d.p., what is the result?
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(C)
6.2
38
What is a good reason to round numbers to 1 s.f. before calculating?
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(A)
To make it easier to multiply or divide mentally.
39
What is 0.8413 rounded to 2 decimal places?
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(A)
0.84
40
Which of the following is the most accurate way to express the answer to a calculation?
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(B)
Giving the answer to a sensible degree of accuracy.
41
What happens to the value of a number when rounded to 1 s.f. if the second digit is greater or equal to 5?
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(A)
The first digit increases by 1
42
What is 1090 to 2 significant figures?
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(C)
1090
43
In the process of estimation, when you calculate 4.7 * 1.9, what do you do first?
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(B)
Round each number to 1 s.f.
44
What is a significant figure?
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(C)
A digit that is not a zero used only to locate the decimal point or show place value.
45
Estimate the result of the calculation: 47.6 x 11.4
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(D)
600
46
What is the value of 0.00674 rounded to 1 significant figure?
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(A)
0.006
47
When is estimation a useful technique?
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B
C
D
48
What is the value of 2.29465 to 2 d.p.?
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(B)
2.30
49
If you're estimating and one of your numbers has 2 decimal places, to how many decimal places should your answer be?
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(B)
2
50
When is it appropriate to estimate an answer?
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(B)
When you are doing a complex calculation and only need an approximate result.
