Prep · Equivalent ratios and unit rates

1. 1.

   Complete the equivalent ratio: 3 : 8 = 12 : ?

   A	B
   3	8
   12	?

   Answer. 32

   Multiply both parts by 4: 8 × 4 = 32.

2. 2.

   A pack of 10 markers costs $23.8. What is the unit price per marker?

   Answer. $2.38

   $23.8 ÷ 10 = $2.38 per marker.

3. 3.

   Elena has 9 red marbles and 2 blue marbles. Write the ratio of red to blue in simplest form.

   Answer. 9 : 2

   Red : blue = 9 : 2 = 9 : 2.

4. 4.

   In Sam’s class, 2 students walk and 6 students bike. What is the part-to-whole ratio of walkers to the class, in simplest form?

   Answer. 1 : 4

   Walkers : class = 2 : 8 = 1 : 4.

5. 5.

   Complete the equivalent ratio: 7 : 4 = 42 : ? Then Theo needs 5 of that amount. What is the total they need?

   A	B
   7	4
   42	?

   Answer. 120

   Multiply both parts by 6: 4 × 6 = 24. Then multiply by 5: 120.

6. 6.

   A pack of 8 markers costs $7.6. Ava needs 16 markers. How much will that cost at the same unit price?

   Answer. $15.2

   Unit price $0.95. 2 packs: $7.6 × 2 = $15.2.

7. 7.

   Malik has 8 red marbles and 8 blue marbles. Write the ratio of red to blue in simplest form. Write a complete answer — Nora will compare with a partner.

   Answer. 1 : 1

   Red : blue = 8 : 8 = 1 : 1.

8. 8.

   In Owen’s class, 7 students walk and 7 students bike. What is the part-to-whole ratio of walkers to the class, in simplest form? Write a complete answer — Sam will compare with a partner.

   Answer. 1 : 2

   Walkers : class = 7 : 14 = 1 : 2.

9. 9.

   Are the ratios 6 : 7 and 12 : 14 equivalent? Write a complete answer — Priya will compare with a partner.

   Answer. yes

   Both simplify to 6 : 7, so they are equivalent.

10. 10.

    A pack of 6 markers costs $7.5. Grace needs 30 markers. How much will that cost at the same unit price?

    Answer. $37.5

    Unit price $1.25. 5 packs: $7.5 × 5 = $37.5.

11. 11.

    Think

    Jonah tried this problem:
    Sam has 9 red marbles and 8 blue marbles. Write the ratio of red to blue in simplest form.
    Jonah wrote -9 : 8. That is not correct. What is the right answer?

    Answer. 9 : 8

    Jonah’s answer -9 : 8 is off. Red : blue = 9 : 8 = 9 : 8.

12. 12.

    Think

    Jonah tried this problem:
    In Owen’s class, 5 students walk and 7 students bike. What is the part-to-whole ratio of walkers to the class, in simplest form?
    Jonah wrote 6 : 12. That is not correct. What is the right answer?

    Answer. 5 : 12

    Jonah’s answer 6 : 12 is off. Walkers : class = 5 : 12 = 5 : 12.

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