RD Sharma Solutions Class 8 Mathematics Solutions for Direct and Inverse Variations Exercise 10.1 in Chapter 10 - Direct and Inverse Variations

Question 10 Direct and Inverse Variations Exercise 10.1

A car is travelling at the average speed of 50 km/hr. How much distance would it travel in 12 minutes?


Let’s consider distance travelled be ‘x’ meter

We know that one hour = 60minutes

50/60 = x/12

By cross-multiplying

50(12) = 60x

600 = 60x

x = 600/60

= 10

∴ The distance travelled in 12min is 10km

Video transcript
"Hello, dear student and Sunita. They are from Lido learning and here to help you with a problem that goes like this a car is traveling at the average speed of 50 km/h how much distance would it travel in 12 minutes? So here we are given the average speed. Okay. Now let's put down our information given in this table that I have prepared below. So we shall write here distance travelled by the car. And here we shall write time taken. So going back to what we are given we are given the speed is equal to Fifty kilometers per hour So let's put that in the table. The distance is 50 kilometers. And per hour when they say 1 hour is equal to Sixty minutes So we shall write 60 minutes here. Now we are writing it in terms of minutes because our question is how much distance would it travel in 12 minutes? So what we have done is the speed we have converted into two values, which we can put down in our table. Okay. Now the question is how much distance wouldn't travel in 12 minutes. So I will put 12 minutes here and we need to find out how much distance it has traveled. So this is our unknown. So let unknown be equal to X. All right. Okay. Now as we know the greater the distance the car travels the more time it will take right. So if it travels 50 kilometers in 60 minutes, we can guess that in 12 minutes. It's going to travel a lot less than 50 kilometers. So you can see that as a distance reduces the time taken to cover that distance will also naturally reduce. So this is a case of direct variation now in direct variation. We know that a constant of proportionality is given by X upon why that is Our exes 50 our why is 60 so We will write the constant as 50 a point 60 Now this constant is also equal to our unknown X upon 12. Right because the ratio is the same. So now it is easy to find X by cross multiplication. So we have 60 in 2 x is equal to 50 into 12 or our X is equal to 50 into 12 a bond 60. So twelve months or twelve twelve fives are 65 ones are five I-10 so our X is equal to 10 or the distance. The car will travel at the speed of 50 km/h will be 10 kilometers. So that's when speed is given we can find out the distance a car will travel in any particular interval of time. I hope you understood the solution to this problem do drop in a comment in the comment section. Please visit our Channel regularly, you will find many homework solutions like this being explained to you subscribe to our Channel also for updates. Thank you."
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