The length, a, of a pencil is 15.3 cm, correct to 1 decimal place - OCR - GCSE Maths - Question 9 - 2018 - Paper 1

To find the error interval for the length of the pencil, we need to consider the meaning of 'correct to 1 decimal place.' This means that the true length could be slightly less than or greater than 15.3 cm.

1. Determine the rounded value: The rounded value is 15.3 cm.

2. Calculate the lower bound: The smallest value that rounds to 15.3 cm is 15.25 cm.

3. Calculate the upper bound: The largest value that rounds to 15.3 cm is just below 15.35 cm. Therefore, we can express this as 15.35 cm (not inclusive).

Thus, the error interval for the length of the pencil is:

$15.25 < a < 15.35$