This post will cover the concepts using examples thus will help you in Application part.
Most of these questions are frequently asked in CAT/BANKING/SSC. Videos will help you reducing the time needed to solve such questions. 2-3 methods are discussed.
1. A total of Rs. 180 is divided among 100 students such that each girl student receives Rs. 2 and each boy student receives Rs. 1.5 . Find the number of girl student.
S: In above question one approach is to go by allegation;
So 60 and 40.
Other approach is to use approach something like this
Total students 100
If boys get all the money 1.5*100=150
Money remaining 180-150=30
Which was due to difference of 0.5
30/0.5= 60 and hence 100-60 = 40
So 60 40 .
2. Amit takes a loan of Rs 10,000, partly at 6% SI and rest at 8% SI. If he pays a total interest of Rs.1500 in 2 yrs, find the amount taken on loan at 6%.
Using Allegation :
Similarly we can see the approach above using Allegations;
If he paid interest all in 12% (6*2)
then he must have paid 1200 Interest
But he is paying here 1500 300 Extra due to 4% difference 300/4%= 7500
So 10,000-75000 = 2500.
3. In CAT , each correct answer fetches 4 marks and each wrong answer fetches a penalty of 1 marks . If a student attempts 48 questions and scores 132 marks, find the number of correct and wrong answers.
A: 36 & 12.
If he attempted all correct 48*4= 192
But his actual score is 132.
Difference is 60 due to difference of 5 So 60/5= 12 wrong.
4. In a zoo, there are only pigeons and rabbits. If there are a total of 200 heads and 560 legs , find the number of pigeons and rabbits.
A: 80 R & 120 P
If all are pigeons 200 heads and 400 legs will be the logic
But extra 160 is due to difference of 2
So 160/2 =80 .
5. I cover a total of 240 km in 6 hrs , partly at 30 kmph and rest at 60 kmph. What is the distance covered at 30 kmph.
A: 120 Km
If you have any questions or doubts please post in the comment section.