Shortcut Tricks To Solve Percentage - 3

Shortcut Rules to Solve Problems on Percentage - 3

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 the value is decreased successively by x% and x%, then the final decrease is given by

$\left( 2x-\frac{{{x}^{2}}}{100} \right)percent$ 

Trick - 2

• If one factor is decreased by x% and the other factor also decreases by y%, then the effect on the product is given by

$\left( x+y-\frac{xy}{100} \right)percent$ 

Trick - 3

• The pass marks is an examination is x%. If a candidate who secures y marks fails by z marks, then the maximum marks is given by

$\frac{100(y+z)}{x}$ 

Trick - 4

• If the price of a commodity decreases by r% then increase in consumption, so as not to decrease expenditure on this item is

$\left[ \frac{r}{(100-r)}\times 100 \right]percent$ 

Trick -5

• If the original population of a town is P, and the annual increase is r%, then the population in n years is given by 

$P{{\left( 1+\frac{r}{100} \right)}^{n}}$  

  
Trick -6

• If the original population of a town is P, and the annual decrease is r%, then the population in n years is given by 

$P{{\left( 1-\frac{r}{100} \right)}^{n}}$ 

Questions for Practice

Q1. Two population of a town was reduced by 12% in the year 1988. In 1989, it was again reduced by 12%. What is the percentage in the population in the beginning of 1990 ? 

Q2. The land holding of a person is decreased by 10% due to late monsoon, the production decreases by 8%. Then, what is the effect on the revenue ?

Q3. A student has to secure 40%marks to get through. If he gets 40 marks and fails by 40 marks, find the maximum marks set for the examination ? 

Q4. If the price of a sugar falls down by 10% by how much percent must a householder increase its consumption, so as not to decrease expenditure in this item ?

Q5. If the annual increase in the population of a town is 4%, and the present number of people is 15625, what will the population be in 3 years ? 

Q6. If the annual decrease in the population of a town is 5%, and the present number of people is 40000, what will the population be in 2 years ? 

Answers

Answer 1. 22.56%

Answer 2. 17.2%

Answer 3. 200

Answer 4. $11\frac{1}{9}percent$ 

Answer 5. 17576

Answer 6. 36100