Upper and Lower Bounds

Question 1:

When x = 8.835 (3 d.p.) and
y = 153 (1 d.p.), find the lower bound of x + y

161.7845

Question 2:

When x = 700 (1 s.f.) and
y = 200 (1 s.f.), find the upper bound of x - y

600

Question 3:

When x = 0.023 (3 d.p.) and
y = 3.99 (2 d.p.), find the upper bound of x × y

0.0938825

Question 4:

When x = 74.9 (3 s.f.) and
y = 40 (1 s.f.), find the lower bound of x ÷ y

1.6633333333333