## Approximations Exercise

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 8.36⁄4.21 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