• # question_answer Ramya has 4 different toys and Saumya has 7 different toys. The number of ways in which they can exchange their toys, so that each keep her initial number of toys are A)  338                             B)  329               C)  330                             D)  331

When we keep the toys of Ramya and Saumya together, the problem is to fixed the number of ways in which Ramya can take 4 toys out of 11 toys, not including the number of ways in which she takes her original 4 toys which can be done in $^{11}{{C}_{4}}-1=\frac{11!}{4!7!}-1=329$