In how many ways can 4 indistinguishable red balls and 2 different blue balls be arranged in a line?
Choose the correct choice from the following
A) 6! B) 30 C) 40 D) 6!/2! E) 4!/2!
The total number of ways in which a total N items, out of which p are identical of one type, q are identical of another type and rest are different, can be arranged in a line is N!/{p!q!}   In the given problem, we have 6 balls out of which 4 are identical.   Hence the number of arrangements possible are 6!/4! = 30   Ans 30
<result>B</result>
In how many ways can 4 indistinguishable red balls and 2 different blue balls be arranged in a line?