1. Problem: Given $a = b + c$ with $b = 7.13$ (correct to 2 decimal places) and $c = 8900$ (correct to 2 significant figures), find the upper bound of $a$. 2. Find upper bounds: - For $b = 7.13$ correct to 2 decimal places, the upper bound is $7.135$ (adding 0.005). - For $c = 8900$ correct to 2 significant figures, the number is rounded to the nearest hundred. So the upper bound is $8950$ (adding 50). 3. Calculate upper bound for $a$: $$a_{upper} = b_{upper} + c_{upper} = 7.135 + 8950 = 8957.135$$ 4. Final answer: Since $a$ should be correct to 3 decimal places, the upper bound for $a$ is: $$\boxed{8957.135}$$