The average age of $5$ sisters is $20 \, \text{years}$. If the age of the youngest sister is $4 \, \text{years}$,what was the average age of the group of sisters at the time of the birth of the youngest sister?

The average of $12$ results is $15,$ and the average of the first two is $14.$ What is the average of the rest?

$A$ batch of $60$ students made an average score of $50$ marks and another batch of $40$ students made an average score of $45$ marks. What is the overall average score?

Refer to the line graph and answer the given question.
Number of candidates who qualified in a given competitive examination from $6$ states during two given years.
What is the average number of candidates who qualified in the given competitive exam from states $Q, S, T$ and $U$ in $2004$?

The average age of $20$ boys in the class is $15.6$ years. Five new boys join and the new average becomes $15.56$ years. What is the average age of the five new boys (in years)?

The sum of three numbers is $98$. If the ratio between the first and second is $2:3$ and that between the second and the third is $5:8$,then the second number is