Answer:
18.5
Explanation:
To determine the upper bound of the width, we need to consider the uncertainty in the given measurement.
Since the length is given as 30 cm, correct to 2 significant figures, we can assume an uncertainty of ±0.5 cm. This means that the actual length could be anywhere between 29.5 cm and 30.5 cm.
Similarly, since the width is given as 18 cm, correct to 2 significant figures, we can assume an uncertainty of ±0.5 cm. This means that the actual width could be anywhere between 17.5 cm and 18.5 cm.
To find the upper bound of the width, we need to consider the largest possible value of the actual width, which is 18.5 cm. Therefore, the upper bound of the width is 18.5 cm.