(b) \(rac{1}{462}\)Let S be the sample space. Then, n(S) = Number of ways in which 6 boys and 6 girls can sit in a row = 12! Let E : Event of 6 girls and 6 boys sitting alternately. Then, the 6 girls and 6 boys can be arranged in alternate position in two ways. Ist way : We start with a boy. Then the arrangement is : B G B G B G B G B G B G ∴ Number of ways of arranging 6 boys in 6 places = 6! Number of ways of arranging 6 girls in 6 places = 6! ∴ Number of ways of arranging 6 boys and 6 girls in alternate places = 6! × 6! Similarly, IInd way : Here we start with a girl. Then the arrangement is G B G B G B G B G B G B ∴ Number of ways of arranging 6 boys and 6 girls alternately this way = 6! × 6!∴ n(E) = 6! × 6! + 6! × 6! = 2 × 6! × 6!∴ n(E) = \(rac{n(E)}{n(S)}\) = \(rac{2 imes6! imes6!}{12!}\)= \(rac{2 imes6 imes5 imes4 imes3 imes2 imes1}{12 imes11 imes10 imes9 imes8 imes7}\) = \(rac{1}{462}\).