1there are 8 stones thus
(8-1)!2!3!3!
??
2 Answers
49i think we have to consider cases.............
when we fix red for reference......arrangements=7!/(3!3!)*1/2
when we fix blue for reference.....arrangements=7!/2!2!3!*1/2
for black=7!/2!2!3!*1/2
adding the 3 we get the answer=7!/2*3!(1/6+1/4+1/4)=7!/3*3!
