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The length, d, of Jamal's car is 4.72m, correct to 2 decimal places - OCR - GCSE Maths - Question 11 - 2020 - Paper 1

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The length, d, of Jamal's car is 4.72m, correct to 2 decimal places. Complete the error interval for the length, d. (b) Jamal travels 430 km, correct to the nearest... show full transcript

Worked Solution & Example Answer:The length, d, of Jamal's car is 4.72m, correct to 2 decimal places - OCR - GCSE Maths - Question 11 - 2020 - Paper 1

Step 1

Complete the error interval for the length, d.

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Answer

Since 4.72m is rounded to 2 decimal places, the last digit (2) could vary by 0.005. Therefore, the error interval for d can be calculated as follows:

  • The smallest possible value for d is 4.72 - 0.005 = 4.715m.
  • The largest possible value for d is 4.72 + 0.005 = 4.725m.

Thus, the error interval is: 4.715extmd<4.725extm4.715 ext{ m} \leq d < 4.725 ext{ m}

Step 2

Calculate the shortest possible time for Jamal's journey:

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Answer

First, we determine the shortest possible distance Jamal travels:

  • The distance of 430 km, correct to the nearest 10 km, implies the smallest value is 425 km.

Next, we find his average speed:

  • The average speed is given as 57.3 km/h, with a possible variation due to rounding to 1 decimal place. Therefore, the minimum average speed is 57.25 km/h.

Using the formula for time, which is: extTime=DistanceSpeed ext{Time} = \frac{\text{Distance}}{\text{Speed}} we can calculate the shortest time:

  • Substituting the values: Time=425 km57.25 km/h7.43 h\text{Time} = \frac{425 \text{ km}}{57.25 \text{ km/h}} \approx 7.43 \text{ h}

To convert hours into hours and minutes:

  • The decimal part, 0.43 hours, is equivalent to: 0.43×6025.8 minutes0.43 \times 60 \approx 25.8 \text{ minutes}

Thus, the total time is approximately 7 hours and 26 minutes when rounded to the nearest minute.

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