Question: "In a village the average age of n people is 42 years. But after the verification it was found that the age of a person had been considered 20 years less than the actual age , so the new average, after the correction, increased by 1. The value of n is:"
I am particularly finding it difficult to deal with increase on both side. Had this been the original value things would have been much easier. What exactly am I missing. Some help about the same will be most welcome.
The sum of everyone's age in the village before the correction in $42n$. After the correction, the sum is now $42n+20$. The question states that that is equal to $43n$.
$$42n+20=43n \Rightarrow n=20.$$