Monday, November 7, 2016

some mathematics on percentage

problem

In an examination total students appeared are 40% girls and rest boys. Now 80% of the boys and 60% of the girls has succeeded in examination. How many % of the total have failed in the examination.


Solution:
When 40 % are the girls , so 60 % are boys. { In totality it is 100%}

When the answer is asking in % number, let us assume that total no os girls and boys are 100.

Now what is happening that out of 60 boys, 80% of the boys have passed.

No of boys have passed is  =  60* 80/100 = 48 No of boys or 48 % of boys have passed.
No of girls passed is =  40* 60/100 = 24 % of the girls have passed.

so  no of boys and girls failed = 100 - (48 + 24) = 28%

Other problem

A person makes a profit of 12 % on selling an article at 10 % discount on the printed price. Find out the ratio of the cost price and printed price 

Cost price is the price in which the seller has purchased the article on which he has to make the profit. 
Printed price is the price which is printed on the packaging of the article. like MRP ( maximum retail price) 

Let us assume the printed price is  Rs. x 

the person sold the article at 10 % discount 

Selling price  x - (10/100)*x

=  Rs. (  x- 0.1x)= Rs.0.9x  

Now the other statement is showing that on selling at Rs. 0.9 he makes a 12 % profit. 
So his purchasing price is 12 % less of Rs. 0.9 x

so cost price or the sellers purchasing price is  =Rs. 0.9 x- (12/100)0.9x = Rs. 0.792 x 

so in terms of ratio  of cost price/ printed price = 0.792 x/ x= 0.792:1


other problem 

By selling an umbrella for Rs. 500 a shopkeeper gains 20 % . During a clearance sale the shopkeeper allows a discount of 10 % on the marked price. What is his gain percentage.


Here marked price is Rs. 500

Cost price of the umbrella is  Rs. 500 - (20/100)*500 = Rs. 400 

Now on clearance sale it is discounted to  10 % , so the new selling price is Rs. 500- (10/100)*500= Rs 450


Now  the item is sold at Rs. 450 against cost price of Rs. 400 

percentage(%) gain  (450-400)/400*100 = 50/400*100 =12.5 %






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