# [CSAT][CAT] Basic Numeracy – Percentages – Base (Tips &Tricks) – 3

Regaining back from our last post :** [CSAT][CAT] Basic Numeracy – Percentages – Concept (Tips & Tricks) – 2**, now lets learn the concept of base of a percentage and how relevant it is in calculations of CAT & UPSC CSAT Prelims questions.

## Base : So what do you think a base of a percentage should be ?

What does it infer ??Does it infer that 80 students have passed the exam.orDoes it infer that 0.80 students have passed the exam. (as we learned in our last article that 80% = 0.80)

**not true**. Why so ?

**“BASE“.**The information given above only means that had there been 100 students in the class 10th of XYZ school, 80 would have passed the CBSE board exam.

**BASE**i.e.

*the number of students in the class 10th for such calculation.*

Lets redefine this question by including a BASE.80% of the students of class 10th having a total strength of 340 from XYZ school have passed the CBSE Board exam.Now we have a BASE i.e. total strength of the class i.e 340.So if the total strength of class 10th in XYZ school were 34080% of 340 = (80/100) x 340 = 272 students passed the exam.

**Let take an another example.**

*Out of a pack of 210 bulbs produced by pantura(imaginary) company 35 are found defective.*

*So percentage (per 100) of defective bulbs is (35/210) x 100 = 16.67 %.*

*So here base is no. bulbs in a pack = 210.*

**Now checking another example :**

*If a number for e.g. 50 is increased by 25% what will be the final number ?**~ will it bet 50 + 25% = 50 + 0.25*

*This 25% is the percentage of a base and here the base is 50.*

*so*

**Final number**will be 50 + 25% of 50 = 50 + (25/100) x 50*= 50 + (1/4) x 50 =*

**62.5**

Comments awaited below in comment section:

**Books to be referred for questions and concept : CSAT**

Books to be referred questions and concept : CAT/MBA

*In the next article I will be coming up with the details of other subtopics and questions related to the sub topics. I will be keeping it at tortoise’s pace as I discussed in my article How CSAT – UPSC Prelims paper – 2 can help you in your sweet journey !!! and you will find that by devoting less than an hour, how you could reach your target of 160+ score.*

*Friends, You can post problems or questions related to this topic at Forum – Prelims Paper -2 . Lets discuss as much questions as possible in forum. *

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Very nice post… Please post for all maths sections

Sir , I didn’t qualified this year .. 🙁 I am very weak in aptitude. How should I improve my Paper 2 ??

How should I start preparation of Prelims examination ??

Nice post… Keep it up @shashank