Shortcut Methods to Solve Questions on Percentage

Shortcut Rules to Solve Problems on Percentage

Effective for IBPS PO - SBI PO Exam

Dear Reader,

Here we will start a series of Quantitative Aptitude Shortcut Tricks for your upcoming SBI - IBPS - SSC and Other Government Competitive Exams. We will try to cover up all topics of the quantitative Aptitude Sections from which question was generally asked.

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Trick – 1

• If three successive discounts of x%, y% and z% are allowed on an amount then a single discount that equivalent to the three successive discounts will be

 $\left[ x+y+z=\frac{xy+yz+zx}{100}+\frac{xyz}{{{100}^{2}}} \right]%$

Trick – 2

• If X litres of oil was poured into a tank and its was still x % empty. Then the capacity of tank is

$\frac{X\times 100}{100-X}litres$

Trick – 3

• To split a number N into two parts such that one part is p% of the other.

The two split parts are $\frac{100}{100+p}\times N$  and $\frac{p}{100+p}\times N.$

Trick - 4

• In ‘A’ litres of x% acidic, liquid, the amount of water to be added to make y% acidic liquid is

$\frac{A\left( x-y \right)}{y}litres$

Trick - 5

• In a recent survey , x% houses contained two or more people. Of those houses containing only one person y% were having only a male. The percentage of all houses which contain exactly one female and no males is given by

 $\left[ \frac{\left( 100-x \right)\left( 100-y \right)}{100} \right]%$

Trick -6

• If one of the sides of a rectangle is decreased by x% and the other is decreased by y%, then the percent value by which area changes is given by

$\left[ x+y-\frac{xy}{100} \right]%decrease$ 

Questions for Practice

Q1. Find the discount equivalent to a discount series of 20%, 10% and 5%.

Q.2 240 litres of oil was poured into a tank and its was still 20 % empty. Find the capacity of tank.

Q3. Split the number 120 into two parts such that one part is 20% of the other.

Q4. What quantity the water should be added to reduce 9 litres of 50% acidic liquid to 30% acidic liquid ?

Q5. In a recent survey , 25% houses contained two or more people. Of those houses containing only one person 20% were having only a male. What is the percentage of all houses which contain exactly one female and no males ?

Q6. In measuring sides of a rectangle, one side is taken 5% in deficit and the other 4% in deficit. Find the error percent in area calculated from the measurement.

Answers

Answer 1. 31.6%

Answer 2. 300 litres

Answer 3. 100 and 20

Answer 4. 6 litres

Answer 5. 60%

Answer 6. 8.8%