Stage 9 - Q1 - 2 marks
A positive whole number rounds to 330 to the nearest 10. Find the smallest and largest allowed original values.
Hint
The allowed original values have a stated spacing.
Stage 9 - Q2 - 2 marks
A positive whole number rounds to 1700 to the nearest 100. Find the smallest and largest allowed original values.
Hint
The allowed original values have a stated spacing.
Stage 9 - Q3 - 3 marks
A positive multiple of 0.1 rounds to 20 to the nearest 1. Find the smallest and largest allowed original values.
Hint
The allowed original values have a stated spacing.
Stage 9 - Q4 - 3 marks
A positive multiple of 0.01 rounds to 5 to the nearest 0.1. Find the smallest and largest allowed original values.
Hint
The allowed original values have a stated spacing.
Stage 9 - Q5 - 4 marks
A positive integer rounds to 40 to the nearest 10. How many integers could it be?
Hint
An inclusive count needs one more than the endpoint difference.
Stage 9 - Q6 - 4 marks
A positive integer rounds to 60 to the nearest 10. How many integers could it be?
Hint
An inclusive count needs one more than the endpoint difference.
Stage 9 - Q7 - 5 marks
Two whole-number counts round to 80 and 210 to the nearest 10. Find the smallest and largest possible combined count.
Hint
The largest integer is one below the excluded halfway endpoint.
Stage 9 - Q8 - 5 marks
A positive whole number is a multiple of 3 and rounds to 100 to the nearest 10. Find all possibilities.
Hint
Apply both conditions, not only the rounding condition.
Stage 9 - Q9 - 5 marks
A positive number is a multiple of 0.1 and rounds to 120 to the nearest whole number. A learner calls 120.49 its largest possible value. Is that allowed?
Hint
Check the precision of the original data, not only the rounded result.
Stage 9 - Q10 - 3 marks
A positive integer is a multiple of 7. It rounds to 300 to the nearest 100 and to 270 to the nearest 10. Find every possible integer.
Hint
The more precise rounding gives a narrower range, but both conditions still need checking.