Mathematics for IGCSE & O level - Estimation (Section 2)
1
When is an exact calculation useful?
Απάντηση
(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?
Απάντηση
(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.
Απάντηση
(B)
$33
4
What does the term 'significant figures' represent?
Απάντηση
(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?
Απάντηση
(D)
Consider the digit to its right.
6
Why is it important to understand significant figures when making estimates?
Απάντηση
(B)
To express the level of precision
7
Which of the following steps are necessary for rounding?
Απάντηση
A
B
C
8
Which of the following is an example of when estimation would be most useful?
Απάντηση
(C)
Calculating the cost of items
9
If rounding a number, how can you be sure the answer is correct?
Απάντηση
(C)
Check the rule for rounding.
10
What is an important consideration when rounding?
Απάντηση
(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?
Απάντηση
(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.
Απάντηση
(D)
70 cm²
13
When rounding to a given number of significant figures, the first non-zero digit should start from...
Απάντηση
(A)
the left of the number
14
When should you not use estimation?
Απάντηση
(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?
Απάντηση
(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?
Απάντηση
(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
Απάντηση
(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?
Απάντηση
(B)
Give the answer to 1 or 2 significant figures
19
When finding significant figures what should you consider?
Απάντηση
(B)
The first non-zero digit.
20
Which statement best describes the concept of estimation?
Απάντηση
(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?
Απάντηση
A
C
22
What is the key reason for using estimation in a real-world scenario?
Απάντηση
(B)
To save time and simplify the problem
23
When rounding 145 to 2 significant figures, what is the answer?
Απάντηση
(B)
150
24
In estimation, to estimate answers to problems, you can round each ___ to 1 significant figure and then carry out the calculation.
Απάντηση
(B)
number
25
What is the main benefit of estimating when doing a complex math problem?
Απάντηση
(B)
To simplify the process
26
Which of the following describes the best use for estimation?
Απάντηση
(B)
To get a quick answer.
27
When is estimating the volume of a cube when its sides are 2.5 cm best?
Απάντηση
(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?
Απάντηση
(B)
It will provide an easy calculation
29
When finding a sensible degree of accuracy, which is correct?
Απάντηση
C
D
30
What is the main point of estimating the length of the truck, if a car is 3.8m long?
Απάντηση
(B)
To use known measures to help the estimation
31
What is the purpose of rounding numbers?
Απάντηση
(C)
To simplify calculations and show a level of precision.
32
What is the approximate value of 0.00987 to 2 significant figures?
Απάντηση
(B)
0.0098
33
What is a useful strategy when estimating the answer to a division problem?
Απάντηση
(B)
Round both the dividend and divisor to one significant figure, then divide.
34
What is 0.072419 rounded to 1 significant figure?
Απάντηση
(A)
0.07
35
If the digit to the right of the desired decimal place is 5 or greater, what do you do?
Απάντηση
(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?
Απάντηση
(B)
2
37
When rounding 6.217 to 1 d.p., what is the result?
Απάντηση
(C)
6.2
38
What is a good reason to round numbers to 1 s.f. before calculating?
Απάντηση
(A)
To make it easier to multiply or divide mentally.
39
What is 0.8413 rounded to 2 decimal places?
Απάντηση
(A)
0.84
40
Which of the following is the most accurate way to express the answer to a calculation?
Απάντηση
(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?
Απάντηση
(A)
The first digit increases by 1
42
What is 1090 to 2 significant figures?
Απάντηση
(C)
1090
43
In the process of estimation, when you calculate 4.7 * 1.9, what do you do first?
Απάντηση
(B)
Round each number to 1 s.f.
44
What is a significant figure?
Απάντηση
(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
Απάντηση
(D)
600
46
What is the value of 0.00674 rounded to 1 significant figure?
Απάντηση
(A)
0.006
47
When is estimation a useful technique?
Απάντηση
B
C
D
48
What is the value of 2.29465 to 2 d.p.?
Απάντηση
(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?
Απάντηση
(B)
2
50
When is it appropriate to estimate an answer?
Απάντηση
(B)
When you are doing a complex calculation and only need an approximate result.
