Math 9 · Unit 2: Expressions and formulae · Cambridge Lower Secondary Maths Stage 9

Questions

1. 1. You already know a lot of mathematical formulae. Match each name with the correct formula.

   • Area of a triangle
   • Volume of a cuboid
   • Area of a parallelogram
   • Circumference of a circle
   • Area of a trapezium
   • Area of a circle

   • C = πd
   • A = ½(a + b)h
   • A = bh
   • A = πr²
   • V = lbh
   • A = ½bh
   Check

2. 2. Work out the number of hours in 1 day, 2 days, 3 days and d days.

   • 24, 48, 72 and 24d
   • 12, 24, 36 and 12d
   • 1, 2, 3 and d
   • 24, 48, 72 and d + 24
   Check

3. 3. The number of hours in d days is H = 24d. How many hours are in 10 days?

   • 34
   • 2410
   • 240
   • 24
   Check

4. 4. Work out the number of days in 1 week, 2 weeks, 3 weeks and w weeks.

   • 7, 9, 10 and 7 + w
   • 7, 14, 21 and w + 7
   • 7, 14, 21 and 7w
   • 1, 2, 3 and w
   Check

5. 5. Which formula gives the number of days D in w weeks?

   • D = w + 7
   • w = 7D
   • D = 7w
   • D = w/7
   Check

6. 6. Work out the total number of days in 1 week and 2 days, in 3 weeks and 4 days, and in w weeks and d days.

   • 12, 34 and 7wd
   • 3, 7 and w + d
   • 9, 25 and 7(w + d)
   • 9, 25 and 7w + d
   Check

7. 7. The total number of days in w weeks and d days is T = 7w + d. Use the formula to work out the total number of days in 2 weeks and 5 days, and in 6 weeks and 3 days.

   • 19 and 45
   • 7 and 9
   • 25 and 63
   • 14 and 42
   Check

8. 8. Complete the workings to make b the subject of the formula A = bh. Fill in the empty boxes.

   Fill the blanks with these.

   • bh
   • A
   • b
   • h
   Check

9. 9. Complete the workings to make b the subject of the formula F = bg. Fill in the empty boxes.

   Fill the blanks with these.

   • b
   • Fg
   • F
   • g
   Check

10. 10. Complete the workings to make b the subject of the formula T = mb. Fill in the empty boxes.

    Fill the blanks with these.

    • T
    • b
    • m
    • T − m
    • Tm
    Check

11. 11. Complete the workings to make b the subject of the formula X = b + rt. Fill in the empty boxes.

    Fill the blanks with these.

    • X
    • X + rt
    • b
    • rt
    Check

12. 12. Complete the workings to make b the subject of the formula M = b − kn. Fill in the empty boxes.

    Fill the blanks with these.

    • M − kn
    • kn
    • M
    • b
    Check

13. 13. Use the formula D = ST to work out the value of D when S = 50 and T = 3, and when S = 120 and T = 1.5.

    • 16.7 and 80
    • 150 and 80
    • 150 and 180
    • 53 and 121.5
    Check

14. 14. Use D = ST to find S when D = 100 and T = 5.

    • 500
    • 95
    • 105
    • 20
    Check

15. 15. Use D = ST to find T when D = 22 and S = 4.

    • 18
    • 5.5
    • 88
    • 6
    Check

16. 16. Stanley is d years old. Polly is 3 years older than Stanley. Max is 2 years younger than Stanley. Which expressions give Polly's age and Max's age in terms of d?

    • Polly d − 3, Max d + 2
    • Polly d + 3, Max d − 2
    • Polly 3d, Max 2d
    • Polly d + 2, Max d − 3
    Check

17. 17. Stanley is d years old. Polly is 3 years older and Max is 2 years younger. Which formula gives their total age T?

    • T = 3d + 5
    • T = 3d − 1
    • T = 3d + 1
    • T = d + 1
    Check

18. 18. Using T = 3d + 1, find T when d = 8.

    • 24
    • 25
    • 12
    • 39
    Check

19. 19. Make d the subject of T = 3d + 1.

    • d = (T − 1)/3
    • d = 3T − 1
    • d = T/3 − 1
    • d = (T + 1)/3
    Check

20. 20. Using T = 3d + 1, find d when T = 34.

    • 11
    • 10
    • 12
    • 103
    Check