Joan makes cups of tea and coffee at a lunch club. Each cup requires 250ml of boiling water. She has a kettle that boils up to 1.7 litres of water each time. She boils 10 litres of water in an urn. She then uses the kettle to boil the rest of the water she needs. Find the least number of times that Joan needs to boil the kettle to make 56 cups. Show how you decide.

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Joan makes cups of tea and coffee at a lunch club - OCR - GCSE Maths - Question 14 - 2019 - Paper 1

Question 14

Joan makes cups of tea and coffee at a lunch club. Each cup requires 250ml of boiling water. She has a kettle that boils up to 1.7 litres of water each time. She bo... show full transcript

Worked Solution & Example Answer:Joan makes cups of tea and coffee at a lunch club - OCR - GCSE Maths - Question 14 - 2019 - Paper 1

Step 1

Find the total amount of water needed for 56 cups

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Answer

Each cup requires 250 ml of water. To find the total amount of water needed for 56 cups, we calculate:

56 ext{ cups} imes 250 ext{ ml/cup} = 14000 ext{ ml} = 14 ext{ litres}

Step 2

Calculate the amount of water remaining after using the urn

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Answer

Joan boils 10 litres of water in the urn. Now, we find out how much more water is needed:

14 ext{ litres} - 10 ext{ litres} = 4 ext{ litres}

Step 3

Determine how many times Joan needs to use the kettle

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Answer

The kettle can boil 1.7 litres at a time. To find the number of kettle boilings required for the remaining 4 litres, we calculate:

ext{Number of boils} = rac{4 ext{ litres}}{1.7 ext{ litres/boil}} \\ ext{Number of boils} ext{ (rounded up)} = ext{ ceil }(2.35) = 3 ext{ times}

Thus, Joan needs to boil the kettle 3 times.

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