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RS Aggarwal Solutions Class 8 Mathematics Solutions for Profit and Loss Exercise 10B in Chapter 10 - Profit and Loss

Question 4 Profit and Loss Exercise 10B

A cellphone was marked at 40% above the cost price and a discount of 30% was given on its marked price. Find the gain or loss percent made by the shopkeeper

Answer:

let us consider the CP of goods as x

The market price of the goods when goods marked above the 40% CP is

Market price = x + (40x/100) = 140x/100 = 1.4x

So the Discount = 30%

Discount amount = 30% of 1.40x = 0.42x

∴ The SP = Market price – Discount

= 1.4x – 0.42x= 0.98x

Since SP is less than CP it’s a loss

We know that, Loss = CP – SP

= x – 0.98x = 0.02x

∴ Loss % = (Loss × 100)/ CP

= (0.02x × 100)/ x

= 2%

Video transcript
hello students welcome to lido homework my name is nidan and in today's q a video we are going to convert this given mixed fractions into decimal so basically mixed fractions consists of two part the whole part and the fraction part the whole part and the fraction part so in order to get the value of this mixed fraction we just need to add the whole part and the fraction part now our task in hand is convert this fraction into decimal so the best way to convert a fraction into decimal is to ensure that the denominator is either 10 100 thousand and so on the powers of ten so let us try to solve the first question the for in the first question 40 is the whole part and 2 by 5 is the fractional part so i need to convert this fraction into decimal in order to do that i have to ensure that the denominator is either 10 100 000 whichever is convenient for us so in our case it is easier to make 5 into 10 right to make 5 as 10. so how can we convert this denominator from 5 to 10 we just need to multiply it by 2. if i multiply the denominator by 2 i should also multiply the numerator by 2 as well so i get the value as follows 40 plus 4 by 10. now i need to convert this fraction into decimal so in order to do that i just need to look at how many zeros are there in the denominator in this case i have only one zero as 10 is my denominator so now we can convert this fraction into decimal by just writing uh the number as it is just writing the numerator as it is and by just placing the decimal point just before the last digit because in this case we have only one zero so we are putting the decimal point just before the last digit in case there was the if the denominator was hundred that means there are two zeros we should have put the decimal point before the last two digit so now we can add these two numbers so in order to add that i need to convert these two numbers into like decimals so basically what do we mean by like decimals like decimal means that the number of digit after the decimal point should be same so here you can see that in the second number the number of digits after the decimal point is 1 but in the first number it is only there is no decimal point right so now we have to convert this 40 into a decimal number and i have to make after that i have to convert it into like decimal so how can we convert into like decimal so i just have to place 1 0 after the decimal point because in the second number also i have one digit after the decimal point right so in the first one also i'm going to put 1 0 after the decimal point and this does not change the value as such so now we can directly add them as follows 0 plus 4 is 4 decimal point 0 and 4 while adding keep in mind to place the decimal point just above the previous decimal point so the answer that we get is 40.4 now similarly in the second question the whole part is 39 the fraction part is 2 by 10. so in this case the denominator is already 10 so i don't need to convert the denominator into any power of 10 so i can write this as 39 plus 0.2 because there is only one 0 at the denominator now in order to add this i'll convert this 39 into like decimal that is by just placing one zero after the decimal point then by adding a point two after eight so zero zero plus two is two decimal point nine three so the answer is 39.2 similarly i can solve the third question by taking the whole part as four and here the fraction part is three by five so in this case also i need to convert the fraction in such a way that the denominator is 10 so how can i do that i have to just multiply the denominator by 2 and i have to also multiply the numerator by 2. so what do i get i get 4 plus 6 by 10 which is 4 plus 0.6 which will further give me 4.6 that's it similarly in the fourth question the whole part is 25 and the fractional plot is part is 1 by 2. now i have to convert the fractional part in such a way that the denominator is 10 so by what number will i multiply i have to multiply the denominator with 5 if i multiply the denominator with 5 i have to multiply the numerator with 5 as well so what do i get i get 25 plus 5 by 10 which can be written as 25 plus 0.5 which will give me 25.5 that's it so this is how you convert the mix fraction into decimal if there is any doubt or any question you can comment below and for such videos you can subscribe to lido bye thank you
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