# Quantitative Aptitude

Quantitative Aptitude

### How to Quickly find Rate of Simple Interest

Simple interest is calculated only on the principal amount, or on that portion of the principal amount that remains. It excludes the effect of compounding. Simple interest can be applied over a time period other than a year, e.g. every month. [mathjax] Simple Interest FormulaA = P(1 + rt) Where: A = Total Accrued Amount

Aptitude Shortcuts

### Shortcut of Combination and Probability

Shortcut 99:    nCr=n!/[r!(n-r)!] Question: In how many ways 2 shirts and 3 pants can be selected from 5 shirts and 7 pants? Answer: Selecting 2 shirts out of 5 = 5C2 = 5!/[2!(5 – 2)!] = 10 Selecting 3 shirts out of 7 = 7C3 = 7!/[3!(7 – 3)!] = 35 Since the two

Aptitude Shortcuts

### Shortcut of Permutation-2

Shortcut 95: Repeated elements      n!/(a!*b!) Question: In how many ways the letters of the word “ENVIRONMENT” can be arranged? Answer: n = 11 Let, a = 2 (E is repeated twice) Let, b = 3 (N is repeated thrice) Number of arrangements = 11!/(2! x 3!) Shortcut 96: Circular arrangement   (n-1)! Question: In

Aptitude Shortcuts

### Shortcut of Permutation-1

Shortcut 91: Events   Dependent=multiplication   Independent =addition Question: There 3 busses from city A to city B and there are 5 busses from city B to city C. In how many ways a person can travel from city A to C through B? Answer: Choosing a bus from city B depends on choosing a

Aptitude Shortcuts

### Shortcut of Calendar and Clocks

Shortcut 87:                              Using the odd days Question: Find the day of birth of MS Dhoni (7 July, 1981), if 31 Dec 1999 is Friday Answer: Days after 7/7/1981 in 1981 = 177 Odd days by normal years from 1982 to 1999 = 14 Odd days by leap years = 4 x 2 = 8

Aptitude Shortcuts

### Shortcut of Heights and Distances

Shortcut 85: Using tanƟ Ɵ                                tan 0                                    0 30                            $1/\sqrt3$ 45                                  1 60                             $\sqrt3$ 90                              $\infty$ Question: A man on a boat saw a tower of height 100m at an angle of 60o. What is the distance between the man and

Aptitude Shortcuts

### Shortcut of LCM and HCF

Shortcut 82: Maximum number of items per group     Take HCF Question: There are 40, 45 and 50 balls in three different colors. They have to be arranged in boxes such that all the boxes will have equal number of balls and same colored balls. What is the maximum number of balls that can be

Aptitude Shortcuts

### Shortcut of Number system

Shortcut 77: Divisibility test Divisibleby                                    Rule 2                            Last digit of a number should be 0,2,4,6, or 8 3                            Sum of the digit should be divisible by 3 4                            Last two digits of a number should be divisible by 4 5                            Last digit of a number should be 0 or 5 6                             Number should be divisible

Aptitude Shortcuts

### Shortcut of Simple and Compound Interest

Shortcut 75: Simple interest $SI=\frac{PNR}{100}$ P = Principle amount invested or borrowed R = Rate of interest per term N = Number of terms Term = duration for which interest is calculated Question: A man invested Rs. 10000 at 4% per annum simple interest. What is the interest he will get at the end of

Aptitude Shortcuts

### Shortcut of Pipes and Cisterns

Shortcut 73: One pipe fills and another empties $\frac{AB}{-A+B}$ Question: Pipe A can fill a tank in 4 hours and pipe B can empty the tank in 5 hours. If both pipes are opened together, how long will they take to fill a complete tank? Answer: A = 4 B = 5 Substitute the values

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