Average age of 12men is 20 years if age of one more is added to it
the average is decreased by one year find out the age of that man
Sum of ages of 12 men = average age * number of men
= 20 *12
Let the age of newly added man = x
therefore average age = sum of ages of 13 men / number of men
19 = (240 + x ) / 13
19*13 = 240+x
247 = 240 + x
247 - 240 = x
7 = x
Therefore the age of the newly added person = 7 years.
Hope this is helpful!!!