The weight of 50 workers is given below:

Weight in Kg. 50 - 60 60 - 70 70 - 80 80 - 90 90 - 100 100 - 110 110 - 120
No. workers 4 7 11 14 6 5 3

Draw an ogive of the given distribution using a graph sheet. Take 2 cm = 10 kg on one axis and 2 cm = 5 workers along the other axis. Use a graph to estimate the following:
(i) the upper and lower quartiles.