The average daily wages of $A, B$ and $C$ is $Rs. 120$. If $B$ earns $Rs. 40$ more than $C$ per day and $A$ earns double of what $C$ earns per day,the wages of $A$ per day is (in $Rs.$)

The average of marks obtained by $150$ candidates in a certain examination is $50$. If the average marks of passed candidates is $55$ and that of the failed candidates is $25$,what is the number of candidates who passed the examination?

The mean of $100$ items was $46$. Later on,it was discovered that an item $16$ was misread as $61$ and another item $43$ was misread as $34$. It was also found that the number of items was $90$ and not $100$. Then,what is the correct mean?

The average of $100$ observations was calculated as $35$. It was found later that one of the observations was misread as $83$ instead of $53$. The correct average is: (in $.7$)

The average age of a man and his two twin sons,born on the same day,is $30 \, \text{years}$. The ratio of the ages of the father and one son is $5:2$. What is the father's age in $\text{years}$?

The average of a non-zero number and its square is $5$ times the number. The number is