Flag Magical Mathematics[Interesting Approach]> permutations combinations...
question mark

out of 3n consecutive number . find number of way in which 3 number can be selected such that their sum is divisble by 3

neeraj singh , 13 Years ago
Grade 11
anser 1 Answers
Chetan Mandayam Nayakar

Last Activity: 13 Years ago

n numbers will leave remainder 0 when divided by 3, n will leave remainder 1, and n will leave remainder 2,

a set of 3 numbers will have a sum divisible by 3 if: let (x,y,z) be the set of remainders when divided by 3,

we require (x,y,z)=(0,0,0),(0,1,2),(1,1,1), (2,2,2), so total number of ways= (n(n-1)(n-2))*4=4n(n-1)(n-2) 

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments