Upper and Lower Bounds

Question 1:

When x = 1700 (2 s.f.) and
y = 9860 (3 s.f.), find the lower bound of x + y

11505

Question 2:

When x = 1000 (1 s.f.) and
y = 23.8 (3 s.f.), find the lower bound of x - y

476.15

Question 3:

When x = 0.701 (3 d.p.) and
y = 5.68 (2 d.p.), find the upper bound of x × y

3.9880275

Question 4:

When x = 920 (2 s.f.) and
y = 52.2 (3 s.f.), find the upper bound of x ÷ y

17.737296260786