Upper and Lower Bounds

Question 1:

When x = 3.912 (3 d.p.) and
y = 4.567 (3 d.p.), find the upper bound of x + y

8.48

Question 2:

When x = 791 (3 s.f.) and
y = 349 (3 s.f.), find the lower bound of x - y

441

Question 3:

When x = 56 (2 s.f.) and
y = 2270 (3 s.f.), find the lower bound of x × y

125707.5

Question 4:

When x = 0.581 (3 d.p.) and
y = 0.48 (2 d.p.), find the lower bound of x ÷ y

1.1969072164948