R. S. Aggarwal Solutions for Chapter: Average, Exercise 2: EXERCISE 6B

The average salary of all workers in a factory is $\mathrm{Rs}.6000$. Out of these workers $150$ are technicians whose average salary is $\mathrm{Rs}.12000$ and the average salary of the remaining workers is $\mathrm{Rs}.3750$. How many workers are in all there in the factory ?

A class consists of two sections A and B consisting of $36$ and $40$ students respectively. In an examination in Mathematics, the average marks obtained by section A is $75$ and that of the whole class is $64.5$. What is the average marks obtained by section B?

The average weight of $25$ students is $28.8 \mathrm{kg}$. By the admission of a new student the average weight decreases by $300$ grams. What is the weight of the new student?

The average of $8$ results is $20.$ Out of these, the average of first two results is $15\frac{1}{2}$ and the average of next three results is $21\frac{1}{3}$. The sixth result is $4$ less than the seventh and $7$ less than the $8\mathrm{th}$. What is the last result?

Continuously for $15$ days, the average income of a man was $\mathrm{Rs}.140$ per day. If for the first $5$ days, the average income be $\mathrm{Rs}.125$ per day and for the last $9$ days, the average income be $\mathrm{Rs}.145$ per day, what was his income for the 6th day?

In a competitive examination for some posts $750$ candidates appeared and their average marks were $48$. The average marks obtained by successful candidates were $78$ and the average marks for the unsuccessful candidates were $42$. How many percent of the candidates were successful in this examination?

In a group of some people type A consists of businessmen and type B that of service men. The average age of the whole group is $27$ years. If the average age of type A be $34$ years and that of type B be $24$ years, find the percentage of each type in the whole group.

A ship is at a distance of $40 \mathrm{km}$ from sea-shore. A hole is created in it through which water enters at the rate of $1\frac{7}{8}$ tons per $6$ minutes. 60 tons of water is sufficient for its sinking. But, there is an outlet in the ship which throws out water at the rate of $12$ tons per hour. What must be the average speed of the ship by which he may reach the bank safely?