UPSC CDS 2 2022 Math Paper

Mean of first n even numbers = (n + 1)
Mean of first n odd numbers = n

According to the question
Let the mean of the first 100 even numbers = M
⇒ (n + 1) = M -----(1)
Mean of first 100 odd numbers = n
⇒ (n + 1) = M
Fromequation (1)
⇒ n = (M − 1)