Direction: The following questions are accompanied by two statements (I) and (II). You have to determine which statements(s) is/are sufficient/necessary to answer the following question.

The average of the four numbers is two times of the fifth number. What is the fifth number?

I : Average of the first two numbers is two more than the average of the next two numbers.

II : Average of the first two numbers is ten more than the fifth number.

III : The average of the all five numbers is 19.8.