Q.

Let b1b2b3b4 be a 4-element permutation with bi{1,2,3,,100} for 1i4 and bibj for ij, such that either b1,b2,b3 are consecutive integers or b2,b3,b4 are consecutive integers. Then the number of such permutations b1b2b3b4 is equal to __________.

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!
An Intiative by Sri Chaitanya

answer is 18915.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

detailed_solution_thumbnail

bi{1,2,3100}  Let A= set when b1b2b3 are consecutive  n(A)=97+97++9798 times =97×98  Similarly when b2b3b4 are consecutive  n(B)=97×98n(AB)=97+97+9798 times =97×98  

 Similarly when b2b3b4 are consecutive 

n(B)=97×98n(AB)=97n(AUB)=n(A)+n(B)n(AB)  Number of permutation =18915

 

Watch 3-min video & get full concept clarity

tricks from toppers of Infinity Learn

score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon
Let b1b2b3b4 be a 4-element permutation with bi∈{1,2,3,……,100} for 1≤i≤4 and bi≠bj for i≠j, such that either b1,b2,b3 are consecutive integers or b2,b3,b4 are consecutive integers. Then the number of such permutations b1b2b3b4 is equal to __________.