CAT Important Formulas: Percentages
To solve Percentages questions of CAT exam, you need to know the following formulas:
To find what percentage of x is y: (y/x) × 100
Increase N by S % = N(1+ S/100 )
Decrease N by S % = N (1 – S/100)
CAT Important Formulas: Time and Work
To solve Time and Work questions of CAT exam, understand and memorise the following formula:
If X can do a piece of work in n days, then X’s 1 day’s work = 1/n
If X’s 1 day’s work =1/n, then X can finish the work in n days.
CAT Important Formulas: Averages
Given below is the formula for Averages. To solve CAT questions based on Averages, you must know these formulas.
Average = (Sum of observations/Number of observations)
CAT Quantitative Aptitude formulas: Simple and Compound Interest
Simple and Compound Interest questions are always there in CAT. To solve the Simple and Compound Interest questions accurately, you should memorise these formulas.
Interest compounded Annually:
Amount= P (1+ R/100)n
Interest compounded half-yearly:
Amount= P (1+R/2) 2n
100
Interest compounded quarterly:
Amount= P (1+R/2) 4n
100
When interest is compounded annually but time is in fraction:
Amount= P (1+ R)3 X P (1+R/2) 4n
100 100
When rates are different for different years, say R1%, R2%, R3% for 1st, 2nd and 3rd year, respectively.
Amount= P (1+R1) + P (1+R2) + P (1+R3)
100 100 100
Present worth of Rs. x due n years hence is given by:
Present worth= _______x_________
P (1+R3)
100
CAT Important Formulas: Probability
Given below is the formula that you must memorise for solving CAT questions on Probability.
Sample Space: When we perform an experiment, then the set S of all possible outcomes is called the sample space.
Event: Any subset of a sample space is called an event.
The probability of Occurrence of an Event:
Let S be the sample and E be an event.
Therefore, P(E) =n(E) / n(S)
CAT Quantitative Aptitude formulas: Logarithm
To crack the questions based on Logarithm, here are the important CAT formulas you need to know:
- loga (xy) = loga x + loga y
- loga (x/y) = loga x – loga y
- logx x = 1
- loga 1 = 0
- loga (xn) = n(loga x)
- loga x = 1/(logx a)
- loga x = (logb x)/(logb a) = (log x)/(log a)
CAT Important Formulas: Set Theory and Function
Given below are the important CAT formulas for Set Theory and Function. If you are thorough with these formulas, you can solve all the questions.
De Morgan’s Law:
(A ∩ B) ‘ = A’ U B’ and (A U B)’ = A’ ∩ B’
The relation R ⊂ A × A is said to be called as:
- Reflexive Relation: If aRa ∀ a ∈ A.
- Symmetric Relation: If aRb, then bRa ∀ a, b ∈ A.
- Transitive Relation: If aRb, bRc, then aRc ∀ a, b, c ∈ A.
If any relation R is reflexive, symmetric and transitive in a given set A, then that relation is known as an equivalence relation.
Permutation Formula: A permutation is the choice of r things from a set of n things without replacement. Order matters in permutation.
Combination Formula: A combination is the choice of r things from a set of n things without replacement. The order does not matter in combination.
CAT Important Formulas: Mixtures and Alligations
To solve questions on Mixtures and Alligations, you must be thorough with the formula given below:
Rule of Alligation:
If two ingredients are mixed, then
(Quantity of cheaper / Quantity of dearer) = (C.P. of dearer – Mean Price / Mean price – C.P. of cheaper)
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