The average of $50$ numbers is $30.$ If two numbers,$35$ and $40$ are discarded,then the average of the remaining numbers is nearly.

The average of nine numbers is $50$. The average of the first five numbers is $54$ and that of the last three numbers is $52$. Then the sixth number is?

Average age of $A, B$ and $C$ is $84 \text{ years}$. When $D$ joins them,the average age becomes $80 \text{ years}$. $A$ new person,$E$,whose age is $4 \text{ years}$ more than $D$,replaces $A$ and the average of $B, C, D$ and $E$ becomes $78 \text{ years}$. What is the age of $A$ (in $\text{years}$)?

The average price of $80$ computers in an electronic shop is $Rs. 30,000$. If the highest and lowest price computers are sold out,then the average price of the remaining $78$ computers is $Rs. 29,500$. The cost of the highest price computer is $Rs. 80,000$. The cost of the lowest price computer is (in $Rs.$): (in $,000$)

The mean of the marks obtained by $100$ students is $60$. If the marks obtained by one of the students was incorrectly calculated as $75$ whereas the actual marks obtained by him were $65$,what is the correct mean of the marks obtained by the students?

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