1. Round off the following numbers to the number of significant figures shown in brackets:

(a) 4.472 (to 3 sig. fig.) (b) 4.49 (to 2 sig. fig.)
(c) 0.0147 (to 2 sig. fig.) (d) 924.4 (to 2 sig. fig.)
(e) 4.794 (to 1 sig. fig.) (f) 0.729 (to 2 sig. fig.)
(g) 4.2447 (to 4 sig. fig.) (h) 92444 (to 1 sig. fig.)
(i) 2.79 × 20.2 (to 2 sig. fig.) (j) 9.42 × 20 (to 2 sig. fig.)

 

2. Round the following to the degree of accuracy stated:
(a) 47 744 people at a football match (to the nearest thousand people)  
(b) A mass of 12.49 kg (to the nearest kg)  
(c) A salary of $32,449 (to the nearest hundred dollars)  
(d) A cricketer's score of 99 (to the nearest ten runs)  

3. (a) In the table below, round each number to 1 significant figure and calculate.

(b) Calculate the answer accurately and round it to 4 significant figures.

 

Calculation

(a) Estimate

(b) Accurate answer (rounded to 4 sig. fig.)

9.47 + 4.7

   

34.5 × 2.9

   

(9.42) 2

   

8.364.21

   

4.99 − (5.74 + 3.2)

   

4.Round off the following numbers to the number of decimal places (d.p.) shown:
(a) 4.79 (to 1 d.p.)
(b) 4.497 (to 2 d.p.)
(c) 0.097 (to 2 d.p.)
(d) 7.2944 (to 3 d.p.)
(e) 427.2994 (to 1 d.p.)
(f) 49.94 (to 0 d.p.)

5. Complete the table, by estimating the cost of each item to 1 significant figure:

Purchase

Estimated cost

Accurate cost

4 cakes at $4.99 each

   

2 buns at 99c each

   

7 biscuits at 22 cents each

   

2 cans of drink at $1.84 each

   

4 loaves at $2.24 each

   

Totals