Percentage

Percentage is defined as the backbone of any calculations.Their is more than 50% campus questions that involve the use of percentage directly or indirectly. I know , that each one of you know how to perform calculation on percentage, but then also i m posting it over here....the question arises why....
The answer is very simple.Its because of the time constraint u r in when u r in the campus examination.I assure you these tips and tricks will help you to reduce your timings by almost 25%. So,friends why to waste 4 minutes when u can do it in 3 minutes...every minute is important...i hope u all agree with it....

So, lets start it

Percentage increase/decrease in quantity = (change in quantity/original quantity) * 100%

If a value p increases by x%,then the resultant value should be decreased by (x/x+100)*100 %to get back to original value p

Percentage decrease = [p*((100+x)/100)-p]/p*((100+x)/100) * 100
=(x/(100+x)*100) * 100 %

TIPS :
If a value p is increased by n/d then to get back p from resultant value, decrease the increased value by (n/n+d).
If a value p is decreased by n/d then to get back p from resultant value, increase the decrease dvalue by (n/d-n)

Some important conversion:

10%=1/10
20%=1/5
25%=1/4
40%=2/5
50%=1/2
60%=3/5
75%=3/4
80%=4/5

Questions:

The price of a Maruti car rises by 30% while the sales of the car comes down by 20%.What is the percentage change in the total revenue?

A person who has a certain amount with him goes to market. He can buy 50 oranges or 40 mangoes. He retains 10% of the amount for taxi fare and buys 20 mangoes and the balance, he purchases oranges. Number of oranges he can purchase is

I bought 5 pens, 7 pencils and 4 erasers. Rajesh bought 6 pens, 8 erasers and 14 pencils for an amount which has half more what I had paid. What percent of the total amount paid by me was paid for the pens?

One bacteria splits in to eight bacteria of the next generation. But due to environment, only 500 of one generation can produce the next generation. If the seventh generation number is 4096 million, what is the number in the first generation?

2/5 of the voters promise to vote for P and the rest promised to vote for Q. Of these, on the last day 15% of the voters went back of their promise to vote for P and 25% of voters went back of their promise to vote for Q, and P lost by 2 votes. Then, the total number of voters is

A report consists of 20 sheets each of 55 lines and each such line consists of 65 characters. This report is reduced on to sheets each of 65 lines such that each line consists of 70 characters. The percentage reduction in the number of sheets closet to

A trader makes a profit equal to the selling price of 75 articles when he sold 100 of the articles.What % profit did he make in the transaction?