Upper and Lower Bounds

Question 1:

When x = 0 (1 d.p.) and
y = 5.333 (3 d.p.), find the lower bound of x + y

5.2825

Question 2:

When x = 3940 (3 s.f.) and
y = 33.7 (3 s.f.), find the upper bound of x - y

3911.35

Question 3:

When x = 250 (2 s.f.) and
y = 33 (2 s.f.), find the upper bound of x × y

8542.5

Question 4:

When x = 11.49 (2 d.p.) and
y = 0.97 (2 d.p.), find the lower bound of x ÷ y

11.779487179487