Ws5 Estimation Approx

Date:

______/______/ 2009

Marks

Worksheet 5: Estimation and Approximation 1

Basic Question (a) (b) (c) (d)

Round off 6.236 to 2 significant figures. Round off 2.5945 to 3 decimal places. Round off 768 254 to 3 significant figures. Write down, correct to the nearest whole number, the value of

3

998

Ans: (a) 6.2 (b) 2.595 (c) 768 000 (d) 10 2

Basic Question Estimate, correct to 2 significant figures, the value of 30.02 ×19.99 − 78.23 . Solution: 30.02 ×19.99 − 78.23 ≈ 30.0 × 20.0 − 78.2 = 600 − 78.2 = 521.8 ≈ 520 [Anglican High School/2007] Ans: 520

3

Intermediate Question Estimate the value of

10.49 × 3 7.995 16.04

, giving your answer correct to 2

significant figures. Solution:

10.49 × 3 7.995 10.5 × 3 8.00 ≈ 16.04 16.0 10.5 × 2 = 4 21 = 4 = 5.25 ≈ 5.3 [Cedar Girls’ Sec School /2008] Ans: 5.3

© Victoria School Math Department

4

Intermediate Question Estimate, correct to 1 significant figure, the value of

13 × 3 26.8 . 0.9012 + 0.693

Solution:

13 × 3 26.8 0.9012 + 0.693 13 × 3 27 ≈ 0.902 + 0.69 13 × 3 = 0.81 + 0.69 39 = 1.5 = 26 ≈ 30

Ans: 30

5

Intermediate Question Estimate, correct to 1 significant figure, the value of

17.31 + 13.13 . 4.041× 898.9

Solution: 17.31 + 13.13 4.041× 898.9 17 + 13 ≈ 4.0 × 900 30 = 4 × 30 = 0.25 ≈ 0.3

Ans: 0.3

© Victoria School Math Department