Trade Mathematics Course: Ratios, proportions and percentages

1. Pregunta 1 de 15

   A job uses a concrete mix of 1 part cement, 2 parts sand and 3 parts gravel (1:2:3) by volume. You use 2 buckets of cement. How many buckets of gravel do you need?

   • A5
   • B4
   • C6
   • D3
   Ver respuesta

   Respuesta: C. 6

   Each part of the ratio is multiplied by the same number. 1 part cement = 2 buckets, so 3 parts gravel = 3 × 2 = 6 buckets.

2. Pregunta 2 de 15

   A two-stroke engine needs fuel mixed at 50:1 (gas to oil). How much oil do you add to 5 L of gas?

   • A250 mL
   • B10 mL
   • C50 mL
   • D100 mL
   Ver respuesta

   Respuesta: D. 100 mL

   5 L = 5,000 mL. 50:1 means 1 part oil for every 50 parts gas: 5,000 ÷ 50 = 100 mL.

3. Pregunta 3 de 15

   A floor needs 420 ft² of flooring. You add 10% for waste and cuts. How much should you order?

   • A504 ft²
   • B378 ft²
   • C462 ft²
   • D430 ft²
   Ver respuesta

   Respuesta: C. 462 ft²

   10% of 420 = 42. Add it on: 420 + 42 = 462 ft² (or 420 × 1.10).

4. Pregunta 4 de 15

   A drain pipe drops 30 mm over a horizontal run of 1.5 m. What is the slope as a percentage?

   • A2%
   • B0.2%
   • C20%
   • D5%
   Ver respuesta

   Respuesta: A. 2%

   Slope % = rise ÷ run × 100. Use the same units: 30 ÷ 1,500 × 100 = 2%.

5. Pregunta 5 de 15

   A 12 m pipe run must slope at 2%. How much lower is the far end?

   • A240 mm
   • B600 mm
   • C2,400 mm
   • D24 mm
   Ver respuesta

   Respuesta: A. 240 mm

   2% of 12 m = 0.02 × 12 = 0.24 m = 240 mm.

6. Pregunta 6 de 15

   A roof has a pitch of 6 in 12 (6 in of rise for every 12 in of run). How much does it rise over a run of 8 ft?

   • A16 ft
   • B2 ft
   • C4 ft
   • D6 ft
   Ver respuesta

   Respuesta: C. 4 ft

   The rise is 6/12 = 1/2 of the run. Half of 8 ft = 4 ft.

7. Pregunta 7 de 15

   Materials cost $1,250. Your company adds a 15% markup. What price do you charge for the materials?

   • A$1,437.50
   • B$1,470.59
   • C$187.50
   • D$1,265.00
   Ver respuesta

   Respuesta: A. $1,437.50

   15% of 1,250 = 187.50. Add it to the cost: 1,250 + 187.50 = $1,437.50.

8. Pregunta 8 de 15

   An invoice in Alberta comes to $2,380 before tax. The GST rate in Alberta is 5%, with no provincial sales tax. What is the total with tax?

   • A$2,618.00
   • B$2,499.00
   • C$2,261.00
   • D$2,689.40
   Ver respuesta

   Respuesta: B. $2,499.00

   5% of 2,380 = 119. Total = 2,380 + 119 = $2,499.00 (or 2,380 × 1.05).

9. Pregunta 9 de 15

   A crew has pulled 360 m of a 480 m cable run. What percentage of the run is done?

   • A133%
   • B25%
   • C75%
   • D80%
   Ver respuesta

   Respuesta: C. 75%

   Part ÷ whole × 100 = 360 ÷ 480 × 100 = 75%.

10. Pregunta 10 de 15

    A crew lays 1,200 blocks in 3 days. At the same rate, how many days will 2,000 blocks take?

    • A5 days
    • B6 days
    • C7 days
    • D4 days
    Ver respuesta

    Respuesta: A. 5 days

    Find the rate: 1,200 ÷ 3 = 400 blocks a day. Then 2,000 ÷ 400 = 5 days.

11. Pregunta 11 de 15

    Four workers can finish a job in 9 days. Working at the same rate, how long would 6 workers take?

    • A13.5 days
    • B6 days
    • C8 days
    • D4 days
    Ver respuesta

    Respuesta: B. 6 days

    More workers means fewer days. Total work = 4 × 9 = 36 worker-days. 36 ÷ 6 = 6 days.

12. Pregunta 12 de 15

    A crew has 4 journeypersons and 6 apprentices. What is the ratio of journeypersons to apprentices in lowest terms?

    • A3:2
    • B4:10
    • C2:5
    • D2:3
    Ver respuesta

    Respuesta: D. 2:3

    Divide both numbers by 2: 4:6 = 2:3. Keep the order the question asks for.

13. Pregunta 13 de 15

    The price of a cable falls from $0.80 to $0.68 per foot. What is the percentage decrease?

    • A17.6%
    • B85%
    • C12%
    • D15%
    Ver respuesta

    Respuesta: D. 15%

    Change = 0.80 − 0.68 = 0.12. Divide by the starting price: 0.12 ÷ 0.80 × 100 = 15%.

14. Pregunta 14 de 15

    A tool lists at $640. You get a 20% contractor discount, then 5% GST is added to the discounted price. What do you pay?

    • A$806.40
    • B$544.00
    • C$537.60
    • D$512.00
    Ver respuesta

    Respuesta: C. $537.60

    Discounted price = 640 × 0.80 = 512. Add GST: 512 × 1.05 = $537.60.

15. Pregunta 15 de 15

    A mortar is mixed 1:3 (cement to sand) by volume. You need 0.24 m³ of dry mix in total. How much cement is that?

    • A0.06 m³
    • B0.08 m³
    • C0.18 m³
    • D0.72 m³
    Ver respuesta

    Respuesta: A. 0.06 m³

    The ratio has 1 + 3 = 4 parts. One part = 0.24 ÷ 4 = 0.06 m³, and cement is 1 part.

Teclado: 1–4 para responder, Intro para la siguiente pregunta.