On the average $$100$$ customers arrive at a place each hour, and on the average the server can process $$120$$ customers per hour. What is the proportion of time the server is idle?

The manufacturing area of a plant is divided into four quadrants. Four machines have to located one in each quadrant. The total number of possible layouts is

Match the following:
List-$${\rm I}$$
(A) Worm gears
(B) Cross helical gears
(C) Bevel gears
(D) Spur gears

List-$${\rm I}{\rm I}$$
1. Parallel shafts
2. Non-parallel, intersecting shafts
3. Non-parallel, non-intersecting shafts
4. Large speed ratios