5.2 Ratio, fractions and linear functions — Practise with help
Try each question first. Open a hint if you are stuck, the next step for one concrete move, and the full working only to check.
Warm-up: remember
Answer these from memory. Do not look back at the section.
- Write with denominator 18.
- Share £56 into 7 equal parts. Work out the value of one part.
Check the warm-up
- .
- , so one part is £8.
If an answer differs, revisit Section 4.1 for equivalent fractions and Section 5.1 for the unitary method.
Practise with help
1. The ratio of red to blue counters is . If the ratio stays the same, how many blue counters go with 8 red counters?
Hint
Set the two ratios equal: .
Next step
The first part grew from 2 to 8, so it was multiplied by 4.
Full working
Multiply the second part by 4: . Check: .
2. 4 cakes use 300 g of flour. How much flour do 9 cakes use at the same rate?
Hint
Find the flour for one cake, then multiply.
Next step
One cake uses g.
Full working
g. Check the rate: g per cake.
3. A straight line passes through and . Write its equation.
Hint
A line through the origin has equation . Find the multiplier .
Next step
The multiplier is .
Full working
The equation is . Check with : .
4. Earlier learning. Write as a fraction with denominator 40.
Hint
, so multiply the numerator and denominator by 5.
Next step
.
Full working
.