RS Aggarwal Class 8 Solutions Chapter 13 Solutions

Time and work are important for RS Aggarwal Class 8 Solutions Chapter 13

Time and Work

• Every job needs a certain amount of time and a certain number of workers, or people who will do the job.
• For example, when we say that ten people need five days to paint a house. In this case, it takes 5 days, 10 people are involved, and the work done is painting the house.
• Most of the time, we count 1 unit of work. This topic is a continuation of what you learned in the last chapter of the RS Aggarwal Class 8 Maths book about direct and inverse proportion.

Work Done

• If Y can finish a job in Z days, then in one day, Y finishes 1Z of the job.
• In the same way, if Y can finish 1Z% of the whole job in 1 day, Y would finish the whole job in Z days.
• If two people, X and Y, can finish a job in W days and Z days, respectively. Then, if they worked together, they could finish the job in (WZW+Z) days.
• If X is A times more efficient than Y, then X would finish a job in (1X)th of the time it takes Y.

Efficiency

• These are two very important ideas when it comes to time and work.
• If the amount of work done stays the same, then the time it takes to do the work is the opposite of how well it gets done.
• This means that as the time it takes to do work goes up, the work gets done less quickly, and vice versa.
• Effectiveness = 1 time

Pipes and Cisterns

Pipes and cisterns is a well-known example of how time and work done can be used together. You need to know that the questions will ask about two different kinds of pipes.

• A pipe called an “inlet” lets water into a tank or container.
• There is a pipe called an Outlet that lets water leave the tank or container.
• If a pipe can fill a tank in “A” hours, then it can fill (1A)th of the tank in “A” hours.
• In the same way, if a pipe can empty a tank in “A” hours, then it will empty (1A)th of the tank in one hour.

Rate of Filling

This idea has something to do with pipes and cisterns. The rate at which a tank or container fills is the opposite of how long it takes for the pipe to fill it. For example, if one pipe can fill a tank in 20 hours and another pipe can fill the same tank in 10 hours, then the rate at which the first pipe fills the tank is faster than the rate at which the second pipe fills the tank.

Chapter 13 of RS Aggarwal Class 8 Solutions is about time and work.

• There are two exercises in the RS Aggarwal Solutions for Class 8 Chapter 13 book. Exercise 13A comprises 19 questions. There are questions about pipes and cisterns, as well as work that has been done. To figure out how to answer these questions right, you need to study the formulas above.
• Exercise 13B has 17 questions. They are also based on the same ideas, but they require a bit more advanced thinking. There are also questions about how well the work is done in this exercise.
• You need to pay close attention to these questions because the calculations can be common. Also, it is not easy to figure out how to solve the word problems in these questions at first.