Upper and Lower Bounds

Question 1:

When x = 1.8 (1 d.p.) and
y = 8.85 (2 d.p.), find the upper bound of x + y

10.705

Question 2:

When x = 4000 (1 s.f.) and
y = 330 (2 s.f.), find the upper bound of x - y

4175

Question 3:

When x = 7300 (2 s.f.) and
y = 70 (1 s.f.), find the upper bound of x × y

551250

Question 4:

When x = 5000 (1 s.f.) and
y = 500 (1 s.f.), find the upper bound of x ÷ y

12.222222222222