Stage 8 - Q1 - 2 marks
Estimate by rounding each factor to 1 s.f.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q2 - 2 marks
Estimate by rounding each factor to 1 s.f.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q3 - 3 marks
Estimate by rounding both values to 1 s.f.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q4 - 3 marks
Estimate by rounding both values to 1 s.f.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q5 - 4 marks
A rectangle measures 28.8 m by 4.91 m. Calculate its area to 3 significant figures. Keep all digits until the last step.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q6 - 4 marks
A rectangle measures 20.4 m by 4.93 m. Calculate its area to 3 significant figures. Keep all digits until the last step.
Hint
Separate the estimate from the calculation using original values.
Stage 8 - Q7 - 5 marks
Estimate \((39.6\times 0.51)/1.98\) using \(1-s.f\). inputs. Then calculate the actual value and compare.
Hint
Round each input separately for the estimate only.
Stage 8 - Q8 - 5 marks
A class has exactly 28 pupils. A calculator gives a mean score of 17.428571. A report asks for one decimal place. Which number should be rounded: the pupil count or the final mean?
Hint
Distinguish exact counted quantities from a rounded reported statistic.
Stage 8 - Q9 - 5 marks
A rectangle has sides 2.46 m and 3.84 m. Compare rounding each side to 1 decimal place before multiplying with multiplying first and rounding the area to 1 decimal place.
Hint
Keep a separate calculation for each rounding strategy.
Stage 8 - Q10 - 5 marks
A carrier may hold 41.9 kg. There are 120 identical items, each with mass 0.348 kg. A pupil rounds each mass to 0.35 kg before multiplying and says the load is too heavy. Decide using the original values and explain the effect of early rounding.
Hint
Compare the accumulated error with the gap to the weight limit.