Q.

Two queens, placed at random on a chess board, the probability that they are not in clashing position is p then 36P19=(queens can move in row, column and diagonally and [.] is GIF)

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 4.

(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

The queens will be facing each other in case both are placed on the same column, the same row or the same diagonal of the chess board. There are eight rows, eight columns, two principal diagonals and four sets each containing  lines of 7,6,5,4,3,2,1 square. Hence the probability of the queens taking on each other is

P(A¯)=188c2+4(7c2+6c2+5c2+4c2+3c2+2c2) 64c2

=18×8×7+4[7×6+6×5+5×4+4×3+3×2+2×1]64×63

=18×7+[7×3+3×5+5×2+2×3+3×1]64×63=18×7+[7×3+3×7+14]8×63

18+6+28×9=2672=1336

Hence the probability that the two queen to not take on each other is P(A)=1 1336=2336

Watch 3-min video & get full concept clarity
score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

whats app icon