A house of 4 rooms is designed from 4 types of bedrooms and 3 types of bathrooms. The house must have at least 2 types of bedrooms and at least 1 type of bathroom. How many ways can this house be designed? Pick one
A) 3  B) 4  C) 12  D) 30  E) 38
Solution: We have two possibilities 3Bed 1Bath or 2Bed 2Bath   (4C3)(3C1)+(4C2)(3C2)=30   30) 30
<result>D</result>
A house of 4 rooms is designed from 4 types of bedrooms and 3 types of bathrooms. The house must have at least 2 types of bedrooms and at least 1 type of bathroom. How many ways can this house be designed?