Upper and Lower Bounds

Question 1:

When x = 80 (1 s.f.) and
y = 5930 (3 s.f.), find the upper bound of x + y

6020

Question 2:

When x = 5.1 (1 d.p.) and
y = 0.167 (3 d.p.), find the lower bound of x - y

4.8825

Question 3:

When x = 750 (2 s.f.) and
y = 9200 (2 s.f.), find the upper bound of x × y

6983750

Question 4:

When x = 6500 (2 s.f.) and
y = 13 (2 s.f.), find the lower bound of x ÷ y

477.77777777778