Quantitative Aptitude is necessary for competitive exams. To succeed in the competitive exams what we need to have is Speed and Accuracy which can be achieved through shortcut techniques.
Let us consider some examples to learn Short Tricks and Formula to solve Quantitative Aptitude Question
Example 1 The age of a father 3 years ago was 7 times the age of his son. At present the age of son is five times the age of son. What are the present age of father and son ?
Solution: Let the present age of son = x years the present age of father = 5x years 3 years ago sons age = x-3 Fathers age = 5x-3 7(x-3) = 5x-3 7x-21=5x-3 2x=18 x=9 So, Present age of son is 9 years and father is 5*9=45.
Shortcut--- Sons Age = T1(x-1)/x-y= 3*(7-1)/(7-5) = 9
Example 2 A sum of money doubles itself in 10years at S.I . What is the rate of Interest. Solution: Let the sum be x After 10 years it becomes 2x Interest= Rs.2x- Rs.x =Rs.x Rate = 100*l/P*T =100*x/x*10 = 10%
Shortcut -- Time*Rate = 100(Multiple Number of Principal Amount -1) Rate= 100 (Multiple Number of Principal Amount-1 ) /Time
Example A sum of money doubles itself in 7 years.In how many years will it become four fold?
shortcut -- Double in 7 years Triple in 14 years 4 times in 21 years 5 times in 28 years
Example When a person covers a distance between his house and office at 50 km/hr . He is late by 20 min. But when he travels at 60km/hr. He reaches 10 min early.What is the difference between his house and office ?
Solution: Let the distance be x km Time taken to cover x km at 50km/hr is = x/50 hrs Time taken to cover x km at 60km/hr is = x/60 hrs Difference between time taken = 30 min ∴x/50-x/60 = 30/60 => 6x-5x/300 = 1/2 => x = 150 km
Shortcut -- Required Distance = Product of two speeds / Difference of two speeds * Difference between arrival time.
So Short cut should written after solving every type of problem in a separate notebook , and remember it well. -This kind of shortcuts saves a lot of time while solving problems. -By following shortcut methods one can solve problems in time with high degree of accuracy