Prep · Scale drawings

1. 1.

   A scale drawing uses a scale factor of 5. The original is 8 cm by 3 cm. What are the drawing’s dimensions?

   Answer. 40 cm by 15 cm

   Multiply each length by 5: 40 by 15.

2. 2.

   A scale drawing uses a scale factor of 3. The original is 3 cm by 4 cm. What are the drawing’s dimensions?

   Answer. 9 cm by 12 cm

   Multiply each length by 3: 9 by 12.

3. 3.

   On a map, 1 cm represents 4 km. A road is 3 cm on the map. How long is the road in kilometers?

   Answer. 12 km

   3 × 4 = 12 km.

4. 4.

   A scale drawing uses a scale factor of 4. The original is 5 cm by 6 cm. What are the drawing’s dimensions?

   Answer. 20 cm by 24 cm

   Multiply each length by 4: 20 by 24.

5. 5.

   A scale drawing uses a scale factor of 5. The original is 4 cm by 2 cm. What are the drawing’s dimensions? Then Elena needs 5 of that amount. What is the total they need?

   Answer. 100 cm by 10 cm

   Multiply each length by 5: 20 by 10. Then multiply by 5: 100 cm by 10 cm.

6. 6.

   A scale drawing uses a scale factor of 4. The original is 8 cm by 3 cm. What are the drawing’s dimensions? Then Jonah needs 2 of that amount. What is the total they need?

   Answer. 64 cm by 12 cm

   Multiply each length by 4: 32 by 12. Then multiply by 2: 64 cm by 12 cm.

7. 7.

   On a map, 1 cm represents 4 km. A road is 6 cm on the map. How long is the road in kilometers? Then Jonah needs 5 of that amount. What is the total they need?

   Answer. 120 km

   6 × 4 = 24 km. Then multiply by 5: 120 km.

8. 8.

   On a map, 1 cm represents 5 km. A road is 3 cm on the map. How long is the road in kilometers? Then Mei needs 3 of that amount. What is the total they need?

   Answer. 45 km

   3 × 5 = 15 km. Then multiply by 3: 45 km.

9. 9.

   A scale drawing uses a scale factor of 3. The original is 6 cm by 3 cm. What are the drawing’s dimensions? Then Priya needs 3 of that amount. What is the total they need?

   Answer. 54 cm by 9 cm

   Multiply each length by 3: 18 by 9. Then multiply by 3: 54 cm by 9 cm.

10. 10.

    A scale drawing uses a scale factor of 2. The original is 7 cm by 5 cm. What are the drawing’s dimensions? Then Ava needs 5 of that amount. What is the total they need?

    Answer. 70 cm by 10 cm

    Multiply each length by 2: 14 by 10. Then multiply by 5: 70 cm by 10 cm.

11. 11.

    Think

    Grace tried this problem:
    A scale drawing uses a scale factor of 3. The original is 8 cm by 5 cm. What are the drawing’s dimensions?
    Grace wrote 25 cm by 15 cm. That is not correct. What is the right answer?

    Answer. 24 cm by 15 cm

    Grace’s answer 25 cm by 15 cm is off. Multiply each length by 3: 24 by 15.

12. 12.

    Think

    Elena tried this problem:
    A scale drawing uses a scale factor of 3. The original is 4 cm by 6 cm. What are the drawing’s dimensions?
    Elena wrote 24 cm by 18 cm. That is not correct. What is the right answer?

    Answer. 12 cm by 18 cm

    Elena’s answer 24 cm by 18 cm is off. Multiply each length by 3: 12 by 18.

Original extra practice. Keys are computed from the items, not guessed.