Upper and Lower Bounds

Question 1:

When x = 6.604 (3 d.p.) and
y = 0.7 (2 d.p.), find the lower bound of x + y

7.2985

Question 2:

When x = 900 (1 s.f.) and
y = 200 (1 s.f.), find the lower bound of x - y

600

Question 3:

When x = 187.1 (1 d.p.) and
y = 93.12 (2 d.p.), find the upper bound of x × y

17428.34375

Question 4:

When x = 400 (1 s.f.) and
y = 58.8 (3 s.f.), find the lower bound of x ÷ y

5.9473237043331