AQA GCSE · Question 17.11 · Statistical Measures and Calculations
This table also shows information about reduced journey times from London. Work out the missing time and percentage in the Preston row.
How to approach this question
1. **Calculate the reduction time in minutes:** Look at the "Preston" row. Subtract the "Journey time after HS2" from the "Current journey time". (128 - 84).
2. **Calculate the percentage reduction:** Use the formula:
Percentage reduction = (Reduction in time / Original time) * 100.
The "Reduction in time" is your answer from step 1. The "Original time" is the "Current journey time" (128).
3. Calculate (Your answer from step 1 / 128) * 100.
4. Round your percentage to a suitable number of decimal places (e.g., one decimal place, like the others in the table).
We need to complete the final row of the table for the journey to Preston.
**1. Reduction time in minutes:**
This is the difference between the current time and the new time.
Reduction = Current time - Journey time after HS2
Reduction = 128 - 84 = 44 minutes.
**2. Percentage reduction:**
The formula for percentage reduction is:
(Reduction / Original Amount) × 100
Here, the reduction is 44 minutes and the original amount is the current journey time, 128 minutes.
Percentage reduction = (44 / 128) × 100
Percentage reduction = 0.34375 × 100
Percentage reduction = 34.375%
Rounding to one decimal place, as in the other examples, gives 34.4%.
So the missing values are **44** minutes and **34.4%**.
Common mistakes
✗ Calculating the percentage based on the new time instead of the original time (e.g., 44/84 instead of 44/128).\n✗ Rounding the percentage incorrectly.\n✗ Making a subtraction error for the time reduction.
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