Question

A company orders a number of bottles from a factory. The 8 machines in the factory could make all the bottles in 5 days. All the machines work at the same rate.For 2 days, only 4 machines are used to make the bottles. From the 3rd day, all 8 machines are used to make the bottles.Work out the total number of days taken to make all the bottles.

Answer 1

We know that
8 machines in the factory could make all the bottles in 5 days
so
100%-----------> 5 days
1 day------------> 100%/5------> 20% with 8 machines
1 machine work at the rate-------> 20%/8-----> 2.5% per day

day 1---------> 4 machines are used to make the bottles-----> 4*2.5%---> 10%
day 2--------> 4 machines are used to make the bottles-----> 4*2.5%---> 10%
day 3-------->8 machines are used to make the bottles-----> 8*2.5%---> 20%
day 4-------->8 machines are used to make the bottles-----> 8*2.5%---> 20%
day 5-------->8 machines are used to make the bottles-----> 8*2.5%---> 20%
day 6-------->8 machines are used to make the bottles-----> 8*2.5%---> 20%
total work in 6 days=[10+10+20+20+20+20]------> 100%

the answer is
6 days