Page 59 - Mathematics

7. Round off each of the following according to the given number of
significant figures.
(a) 12.7831 correct to 4 significant figures.
(b) 321.045 correct to 2 significant figures.
(c) 0.007138 correct to 3 significant figures.
(d) 37.205 correct to 4 significant figures. Tanzania Institute of Education
(e) 37.207 correct to 1 significant figure.
(f) 399.603 correct to 4 significant figures.
8. A car is equiped with two front bulbs, two rear parking bulbs and a license
bulb. Each front bulb consumes 4.328 watts, the rear bulb consumes
3.432 watts and the license bulb consumes 5.634 watts. Calculate the
total power consumed by the bulbs, giving your answer correct to 3
significant figures.
9. A total of 24,582 people attended a political rally in a certain country.
Round this number to 1 and 2 significant figures and state the most
correct figure you could report to a newspaper company.
10. The following data shows the number of people who travelled by bus
in seven days in a certain country:
20192, 18800, 23468, 25477, 18991, 26060, and 22645.
Find the total number of passengers correct to 2 significant figures.

Approximations in calculations
When working out some calculations involving numbers, sometimes it is important
to find an estimate of the answer. To find an estimated answer, take a suitable

approximation by rounding off the numbers involved. A suitable estimation can
be to round off a number to the nearest whole number or in simple decimals which
enables you to estimate the given problem easily and quickly.

Example 3.18

Estimate the value of 38 71× .

Solution
For easy estimation, round off 38 and 71 to the nearest tens. Mathematics Form One

That is,38 71 40 70× ≈ × = 2 800 .
Therefore,38 71 2 800× ≈ .

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25/10/2024 09:51:15
Mathematics form 1.indd 53
Mathematics form 1.indd 53 25/10/2024 09:51:15