Upper and Lower Bounds

Question 1:

When x = 0.5 (1 d.p.) and
y = 589.1 (1 d.p.), find the upper bound of x + y

589.7

Question 2:

When x = 10000 (1 s.f.) and
y = 1340 (3 s.f.), find the upper bound of x - y

9165

Question 3:

When x = 0.27 (3 d.p.) and
y = 6.964 (3 d.p.), find the lower bound of x × y

1.87666325

Question 4:

When x = 2.12 (3 d.p.) and
y = 0.11 (2 d.p.), find the lower bound of x ÷ y

18.430434782609