A machine can insert letters in envelopes at the rate of 120 per minute. Another machine can stamp the envelopes at the rate of 3 per second. How many such stamping machines are needed to keep up with 18 inserting machines of this kind?
18 inserting machine = (2×18)/sec = 36/sec 1 Stamping machine = 3/sec 1×12 Stamping machine = (3×12)/sec = 36/sec Therefore 12 Stamping machines will be able to keep up with 18 inserting machines.
If 2 workers can complete painting 2 walls in exactly 2 hours.
How many workers would be needed to paint 18 walls in 6 hours?
A large milk-can holds twice the amount of milk a small milk-can hold. The capacity of a jug is 2 litres. If the large milk-can has a capacity of 12 litres. How many jugs of milk are needed to be fill the 1 small milk-can to the brim?
There are three keys to the three doors with different locks on them.
How many attempts would be needed to determine the exact keys for all the doors under all circumstances?
