$A, B, C$ and $D$ are four consecutive odd numbers and their average is $42$. What is the product of $B$ and $D$?

The average of five numbers is $27$. If one number is excluded,the average becomes $25$. The excluded number is

The mean daily profit made by a shopkeeper,in a month of $30$ days,was $Rs. 350$. If the mean profit for the first $15$ days was $Rs. 275$,then the mean profit for the last $15$ days would be (in $Rs.$)

The average of marks of $28$ students in Mathematics was $50$. $8$ students left the school,then this average increased by $5$. What is the average of marks obtained by the students who left the school?

The average of four consecutive odd numbers is $40$. What is the largest number?

If the average of the ages of Rakesh and Mohan is $15$,the average of the ages of Mohan and Ramesh is $12$,and the average of the ages of Rakesh and Ramesh is $13$,then what is the age of Mohan?