Stage 9 - Q1 - 2 marks
A positive measurement rounds to 54 to the nearest 1. Write its error interval.
Hint
Use half the rounding unit on either side.
Stage 9 - Q2 - 2 marks
A positive measurement rounds to 12.2 to the nearest 0.1. Write its error interval.
Hint
Use half the rounding unit on either side.
Stage 9 - Q3 - 3 marks
A positive measurement rounds to 1200 to the nearest 100. Write its error interval.
Hint
Use half the rounding unit on either side.
Stage 9 - Q4 - 3 marks
Identify the rounded value and rounding unit.
Hint
Find both the centre and the width.
Stage 9 - Q5 - 4 marks
Two lengths both round to 20 cm to the nearest cm. Must their exact lengths be equal?
Hint
Give two distinct values inside the shared interval.
Stage 9 - Q6 - 4 marks
Two lengths both round to 22 cm to the nearest cm. Must their exact lengths be equal?
Hint
Give two distinct values inside the shared interval.
Stage 9 - Q7 - 5 marks
A measured length rounds to 2.9 m to the nearest 0.1 m. Could its exact value be 2.95 m?
Hint
Check whether the upper endpoint is included.
Stage 9 - Q8 - 5 marks
A continuous measurement rounds to 65 units to the nearest unit. Describe its error interval and explain whether it has a greatest possible original value.
Hint
An excluded upper bound is not an attained maximum.
Stage 9 - Q9 - 5 marks
A learner says every value rounding to 54 to the nearest unit lies between 53.5 and 54.4, inclusive. Explain the gap.
Hint
Try a value with two decimal places near the upper boundary.
Stage 9 - Q10 - 3 marks
The same positive continuous value rounds to 8 to the nearest unit and 7.5 to the nearest tenth. Find the narrowest interval allowed by both statements. Does it have a greatest possible value?
Hint
Keep only the overlap of the two rounding intervals.