Ratio

Advanced Math 5 · Unit 13 · ratio-tape-diagrams · Teacher edition

ratio-tape-diagrams

Name ______________________________Date ______________

1.
Mia mixes red and white paint in the ratio $3:4$ . She uses $12$ cups of red paint. How many cups of white paint does she use?
Answer: ______________
2.
Ali and Bea have $30$ beads altogether, in the ratio $2:3$ . Ali gives Bea some beads, and now the ratio of Ali's beads to Bea's beads is $1:4$ . How many beads did Ali give to Bea?
Answer: ______________
3.
The red and blue beads on a necklace are in the ratio $3:5$ . The necklace has $40$ beads. How many are red?
1. (A)
  $5$
2. (B)
  $15$
3. (C)
  $24$
4. (D)
  $25$

Answer key — Ratio

1.
16ratio-tape-diagrams-01
$1$ unit $= 4$ cups; white $= 4 \times 4 = \mathbf{16}$ cups.
2.
6ratio-tape-diagrams-02
Before: $30 \div 5 = 6$ per unit, so Ali $12$ , Bea $18$ . After: still $5$ units for $30$ , so Ali has $1 \times 6 = 6$ and Bea $24$ . Ali gave $12 - 6 = \mathbf{6}$ beads. Check: $6:24 = 1:4$ . ✓
3.
(B)
$15$
ratio-tape-diagrams-03
One part $= 40 \div 8 = 5$ ; red $= 3 \times 5 = \mathbf{15}$ . ( $24$ is $\frac{3}{5}$ of $40$ — the ratio read as a fraction of the whole; $25$ is the blue count; $5$ is one part.)