Time, money & unit conversions
AQA GCSE Maths revision on Time, money & unit conversions. Aligned to the AQA GCSE Mathematics 8300 specification. This bank has 16 practice questions on this topic.
Sample questions (3 of 16)
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Question 1
A student calculates the cost of electricity using the formula: Cost = Power (kW) * Time (hours) * Price (p/kWh). If they use the time in minutes instead of hours, why will their answer be incorrect?
- A) The units of time do not match the units of the price per kWh.
- B) The power value needs to be converted to Megawatts.
- C) The price per kWh is only valid for values less than 60.
- D) The calculation requires the use of seconds instead of minutes.
Show answer
Answer: The units of time do not match the units of the price per kWh.
The unit 'kWh' explicitly includes 'hours' as the time component. If you input time in minutes, you are not matching the 'h' in the unit, leading to a calculation that does not represent the energy consumption correctly.
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Question 2
When converting a speed from kilometres per hour to metres per second, why do we divide the number of kilometres by 3.6?
- A) Because there are 3.6 kilometres in a metre.
- B) Because 3600 seconds divided by 1000 metres equals 3.6.
- C) Because it is the standard constant for all velocity conversions.
- D) Because 1000 metres divided by 3600 seconds equals 1/3.6.
Show answer
Answer: Because 1000 metres divided by 3600 seconds equals 1/3.6.
To convert km/h to m/s, you multiply by 1000 (metres per km) and divide by 3600 (seconds per hour). Since 1000/3600 simplifies to 1/3.6, dividing by 3.6 is the mathematical shortcut for this double conversion.
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Question 3
A currency exchange website states: 'We use the mid-market rate but charge a 2% service fee.' If you want to find the final amount received, what is the correct conceptual step?
- A) Calculate 2% of the total and add it to the result.
- B) Multiply the total by 0.98.
- C) Divide the result by 1.02.
- D) Subtract 2 from the exchange rate before multiplying.
Show answer
Answer: Multiply the total by 0.98.
If a service takes 2% of your money as a fee, you are left with 98% of the original converted value. Multiplying by 0.98 is the most efficient way to apply a 2% reduction to the total.
Want to test yourself on the remaining cards for this topic?
13 more questions on Time, money & unit conversions — plus mistakes tracking and spaced repetition across the whole Maths spec.