Combinations and Permutations
Combinations and Permutations
Permutation and combination related questions are common in PSC and Bank exams.
Before going to Combinations and Permutations, first lean about factorial.
If n is a positive integer then, factorial of n is denoted as n!.
5! = ( 1 x 2 x 3 x 4 x 5 ) = 120
4! = (1 x 2 x 3 x 4 ) = 24
Permutations are for lists of items, whose order matters and combinations are for group of items where order doesn’t matter. in other words,
- When the order of items doesn\\\'t matter, it is called as Combination.
- When the order of items does matter it is called as Permutation.
The number of permutations of n objects taken r at a time is determined by using this formula:
P(n,r)=n!/(n−r)!
Permutation: Listing your 3 favourite football team in order, from list of 10 teams. P(10,3) = 720.
The number of combinations of n objects taken r at a time is determined by using this formula:
C(n,r)=n!/((n−r)!r!)
Combination: Picking a team of 3 people from a football coaching group of 10. C(10,3) = 10!(3!(10−3)!) = 120.
Code: ഇപ്പൊ ഭിക്ഷയ്ക്കു അവിടെ പോഡി .
ഇപ്പൊ ഭി - ഹെപ്പറ്റൈറ്റിസ് ബി .
ക്ഷ - ക്ഷയം .
അ - അഞ്ചാം പനി .
വി - വില്ലൻ ചുമ .
ടെ - ടെറ്റനസ് .
പോ - പോളിയോ .
ഡി - ഡിഫ്ത്തീരിയ.
...
Shortcut tricks on boats and streams are one of the most important topics in exams. These are the formulas and examples on Boats and Streams (Cyclist and the wind or Swimmer and stream) questions. These examples will help you to better understand shortcut tricks on boats and streams questions.
There are multiple types of questions asked from these topics. The speed of the boat in still water and the speed of stream will give in questions, You have to find the time taken by boat to go upstream and downstream. .
The speed of the boat in up and down stream will give in question, you need to find the average speed of the boat.
The speed of boat to go up or down the stream will give in question, you need to find speed of boat in still water and speed of stream.
The time taken by boat to reach a place in up and downstream will given in question, you need to find the distance to the place.
LINE_F...
P - Principal, the sum of money lent or borrowed. .
R - Rate of interest: Annual interest, often expressed as a percentage. .
T - Time period for which the money is lent or borrowed. .
Simple Interest = Principal * Time * Rate of interest / 100 .
SI = 4000× 8% × 4 = 4000× 0.08 × 4.
= 1280. .
In compound interest , the principal amount with interest after the first time period becomes the part of principal for the next time period.
CI = [P (1 + R/100)^T] – P .
Total amount = [P (1 + R/100)^T] .
If time period is half-yearly, .
Amount = P[1 + (R/2)/100]^2T .
If time period is quarterly, .
Amount = P[1 + (R/4)/100...
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