Answer:
New machine, working alone will take 20 hours to complete 20000 aluminium cans.
Solution:
For sake of simplicity let’s assume new machine be Machine “N” and old machine be Machine “O”
Let’s assume cans manufacture by machine “O” in 1 hour = x
Since machine N is three times faster than “O”,
So cans manufacture by machine N in 1 hour = 3x
Cans manufactured in 1 hour when both machines are operating simultaneously is equal to cans manufacture by machine O in 1 hour + cans manufacture by machine N in 1 hour
That is cans manufactured in 1 hour when both machines are operating = x + 3x = 4x
So cans manufactured in 15 hours when both machines are operating = [tex]15 \times 4x = 60x[/tex]
Given that cans manufactured in 15 hours when both machines are operating = 20000
60x = 20000
[tex]3x \times 20 = 20000[/tex]
[tex]3x = \frac{20000}{20}[/tex]
3x = 1000 cans
As cans manufacture by machine N in 1 hour = 3x = 1000
So number of hours required by machine N to produce 1000 cans alone = 1 hour
So number of hours required by machine N to produce 1 can alone = [tex]\frac{1}{1000}[/tex] hours
And number of hours required by machine N to produce 20000 cans = [tex]20000 \times \frac{1}{1000}[/tex] = 20 hours
Hence new machine, working alone will take 20 hours to complete 20000 cans.