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

by Wonder Boy · Published December 5, 2014 · Updated December 16, 2014

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 ?

Let’s say, 80% of the students of class 10th from XYZ school have passed the CBSE Board exam.

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

Clearly both the cases are not true. Why so ?

Because we are missing something. The data given here is incomplete without a “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.

But we still don’t know how many students have actually passed the Exam.

So we require a 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 340
80% 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

Articles for Topic Percentage :

1. Basic

2. Concept of percent

3. Concept of Base

4. Multiplying Factor

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.

If you have articles on Quant/DI/Verbal/LR/CR/SC/GS which could be published, feel free to send it to us at [email protected], we will publish it with your contributor account and your pic :). The article should be original & compiled by you and not fully copied from other websites.

Amit Bhilare says:

December 5, 2014 at 6:32 pm

Very nice post… Please post for all maths sections

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Mithil Patel says:

December 5, 2014 at 6:31 pm

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

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Arthav says:

December 5, 2014 at 6:29 pm

How should I start preparation of Prelims examination ??

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Garima says:

December 5, 2014 at 6:28 pm

Nice post… Keep it up @shashank

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