1. Limits of Accuracy

2. What are they?
Any measurement we make is rounded to some degree of accuracy or other
Nearest metre
Nearest litre
The degree of rounding gives the possible values of the measurement before rounding

3. For example A lighthouse is 76m tall, measured to the nearest metre 77
75.5 ≤ Height < 76.5
…..
76.5
Limits of
Accuracy 76
75.5 75

4. Example 2 A car is 2.6m long, measured correct to 1 decimal place
The range of values
between the Upper &
Lower Bounds is often
referred to as
the rounding error
2.55 ≤ Length < 2.65
2.50
2.6
2.60
2.70
2.55
2.65
Lower Bound
Upper Bound

5. Problems involving accuracy
When we calculate an area or a volume, the errors in the measurements will give an even larger error
For example, a room is
measured as 6.4 x 4.3 metres,
measured to 1 decimal place.
Calculate the Limits of
Accuracy of the area of the room

6. 6.35m
6.4m
6.45m
4.35m
4.3m
4.25m
MINIMUM AREA
6.35 x 4.25
= m2
= 26.99m2 (2 dp)

7. Limits of Accuracy
6.35m
6.4m
6.45m
26.99 ≤ Area < m2
4.35m
4.3m
4.25m
MAXIMUM AREA
6.45 x 4.35
= m2
= m2 (2 dp)

8. Val is in training for a 400 metre race
Val is in training for a 400 metre race. He states that he can run 400 metres in 44 seconds. Both of these measurements are given to two significant figures. Find his maximum speed.
395 m
400 m
400 m
405 m
43.5 s
44 s
44.5 s
Max speed = Greatest distance
Shortest Time
speed = 405
43.5
speed = distance
time
speed = … m/s
Max speed is
the Greatest distance
in the Shortest Time
speed = 9.3 m/s (1 dp)