# Unit 17 Section 5 : Problems in context

In this section we look at problems where we need to deal with more than one type of unit.
The units might be metric, or imperial, or both.

## Example Question

A school canteen buys a 1 gallon can of fruit juice.
The canteen sells fruit juice in cups which hold 150 ml of juice.

How many cups can be filled?

We need to get all the amounts into the same units. It is usually easier to change
the bigger unit into the smaller unit, so we will convert the gallons into millilitres.

1 gallon is approximately 4.5 litres, and 1 litre is 1000 ml, so 1 gallon is about 4500 ml.

Now we can answer the question - how many 150 ml cups can we get from 4500 ml?

4500 ÷ 150 = 30, so we can fill about 30 cups from 1 gallon.

## Practice Questions

Work out the answer to each of these questions then click on the button marked to see whether you are correct.

Practice Question 1
Some students take part in a 20-mile sponsored relay run, where each student runs 3000 m and then another takes over.
If each student runs only once, how many students are needed to complete the run?

Practice Question 2
A technology teacher has a 50-yard roll of glass fibre tape.
For a project, each student in the class will need 80 cm of tape, and there are 30 students in the class.
How many metres of tape will be left over?

## Exercises

Work out the answers to the questions below and fill in the boxes. Click on the button to find out whether you have answered correctly. If you are right then will appear and you should move on to the next question. If appears then your answer is wrong. Click on to clear your original answer and have another go. If you can't work out the right answer then click on to see the answer.

Question 1
A glass holds 50 ml of drink.

(a) How many glasses can be filled from a 1 litre bottle?

(b) How many glasses can be filled from a 1 gallon can?

Question 2
A sheet of wood measures 4 feet by 8 feet.
A teacher cuts up the sheet into smaller pieces that measure 10 cm by 20 cm.

How many of these smaller sheets can the teacher make?

Question 3
A baker buys a 25 kg sack of flour. He uses 1 lb of flour for each loaf.

How many loaves can he make with 1 sack of flour?

Question 4
A can contains 2 pints of milk.

How many 125 ml glasses can be filled from the can?

Question 5
A shelf is 3 feet long.

How many books of width 2.5 cm can be put on the shelf?

Question 6
The average length of a car is 4 m, and a bumper-to-bumper traffic jam contains 2000 cars.

(a) How long is the traffic jam in kilometres?
km

(b) How long is the traffic jam in miles?
miles

Question 7
The length of a domino is 2 inches. A group of children placed dominoes end-to-end to form a line of length 100 m.

How many dominoes did they use?

You have now completed Unit 17 Section 5
 Your overall score for this section is Correct Answers You answered questions correctly out of the questions in this section. Incorrect Answers There were questions where you used the Tell Me button. There were questions with wrong answers. There were questions you didn't attempt.
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