9 grade maths> 5 boya and 3 girls seated in a row.find t...

5 boya and 3 girls seated in a row.find the probability that all girl sits alternate?

Manish , 8 Years ago

Grade 12th pass

2 Answers

Vaibhav

Last Activity: 8 Years ago

First arrange boys by factorial 5 ways now as □ □ □ □ □ as shown in arrangements there will be 6 blank space then arrange girls by 6C3 ways final answer will be (factorial5 ×6C3)÷factorial8

Piyush Kumar Behera

Last Activity: 8 Years ago

@vaibhav

the above solution is completely wrong,this is for those questions which give condition that no 2 girls are sitting together,but it is given that all girls are sitting alternate.

for this do the following.Arrange the girls in alternate position G G G and the girls can be arranged in 3! ways among themselves..

THEN THE FOLLOWING CASES ARE POSSIBLE

B B B G B G B G --- girls can be arranged in 3!xboys be arranged in 5! ways

B B G B G B G B --- girls can be arranged in 3!xboys be arranged in 5! ways

B G B G B G B B --- girls can be arranged in 3!xboys be arranged in 5! ways

G B G B G B B B --- girls can be arranged in 3!xboys be arranged in 5! ways

so probability= 4x3!x5!/8!=1/14