Let the average score of the aspirant in all the tests be x. Let the number of tests be n.
The aspirant's average score for the first 10 tests and last 10 tests are 20 and 30 respectively.
nx-200/n-10 = x+1 and nx-300/n-10 = x-1
Solving, we get n=60
What is the sum of ages of Murali and Murugan?
Statements: I. Murali is 5 years older than Murugan.
Statements: II. The average of their ages is 25