19 Juice and water are mixed together in the ratio 2 : 7
(a) Draw a straight line graph that shows the amounts of juice and water to mix together.
Your graph must show up to 10 litres of juice. [2 marks]
(b) How much water needs to be mixed with 5 litres of juice? [1 mark]
Mark scheme (a)
Answer
Mark
Comments
Straight line from (0, 0) to (10, 35)
B2
\(\pm \dfrac{1}{2}\) square B1 one correct point \(\pm \dfrac{1}{2}\) square from (2, 7) to (10, 35) seen or plotted or one correct ratio apart from 2 : 7 or one correct pair of amounts apart from 2 juice 7 water
Additional guidance
Mark intention
If no points plotted, a correct point from (2, 7) to (10, 35) can be implied by a straight line with positive gradient
Two points plotted with the same \(x\)-coordinate is choice unless the line is drawn through one of the points
Condone straight line from (2, 7) to (10, 35)
B2
(2, 7) seen with graph not drawn or incorrect
B1
10 : 35 seen with graph not drawn or incorrect
B1
6 juice 21 water with graph not drawn or incorrect
B1
Mark scheme (b)
Answer
Mark
Comments
Alternative method 1 – uses the given ratio
17.5
B1
Alternative method 2 – uses their graph
Correct water reading for 5 litres of juice from their straight line
