DSE 數學科：數與估算

1. A positive number is written as 4.8 × 10^4. What is its value?

2. Simplify (2^3 × 2^5) / 2^4.

3. A length is measured as 12.5 cm, correct to the nearest 0.1 cm. What is the maximum absolute error?

4. The exact length of a wire is 80 cm. An estimate is 76 cm. What is the percentage error?

5. $5000 is invested at 4% per annum, compounded yearly, for 3 years. Which expression gives the amount?

6. Simplify (a^2 b^(−3))^2 / a^(−1), where a ≠ 0 and b ≠ 0.

7. On a map of scale 1 : 25 000, a road is 6 cm long. What is its actual length?

8. Which of the following is equal to 8^(2/3)?

9. A price decreases by 20% and then increases by 20%. What is the overall change?

10. Which of the following is 0.000456 written in scientific notation?

11. A town has population 2.4 × 10^5. After a 5% increase, which figure is correct?

12. A car travels 180 km in 2 hours 15 minutes. What is its average speed in km/h?