Chapter 13
Numerical Estimation
Chapter 13
1.
Round off 21.467 to
(a) the nearest ten,
(b) 2 decimal places.
(2 marks)
2.
(a) Round off 531.89 to the nearest integer.
(b) Round down 531.89 to 1 decimal place.
(c) Round up 531.89 to 2 significant figures.
(3 marks)
3.
Estimate the value of
1 6
 , correct to
8 11
(a) 3 decimal places,
(b) 5 significant figures.
(3 marks)
4.
Estimate the value of 189.4  9.6 + 14.53 by
(a) rounding off each number to the nearest integer,
(b) rounding up each number to the nearest integer,
(c) rounding down each number to the nearest integer.
(6 marks)
5.
There are 304 pages in a dictionary. Each page has 28 vocabularies. A man wants to learn all the
vocabularies in 365 days.
(a) Estimate the daily number of vocabularies the man learns by
(i) giving the answer correct to 1 significant figure,
(ii) rounding off each number to 1 significant figure.
(b) Which of the estimation methods in (a) gives a more accurate result?
(6 marks)
6.
The weight of a box of chocolate is 955 g.
(a) If there are 16 packs of chocolate in the box, find the weight of each pack of chocolate correct
to 2 decimal places.
(b) If there are 3 chocolates in each pack, find the weight of a chocolate correct to 2 decimal
places.
(6 marks)
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Chapter 13
7.
Numerical Estimation
Carol wants to buy 4 tables priced at $2174, $1632, $2299 and $1130 in a shop.
(a) Estimate the total price of the 4 tables by
(i) rounding off the price of each table to the nearest hundred dollars,
(ii) rounding down the price of each table to the nearest hundred dollars,
(iii) rounding up the price of each table to the nearest hundred dollars.
(b) The budget of Carol for buying the tables is $7500. Using the results of (a), determine whether
the total price of the 4 tables exceeds the budget of Carol. Explain your answer.
(c) Carol can get a free chair if she purchases $7000 or above in the shop. Using the results of (a),
determine whether Carol can get a free chair. Explain your answer.
(10 marks)
2