Acoffee pot makes 6 cups of coffee in 1 1/2 min. how many cups of coffee can the coffee pot make in 1 min?

There are several information's that are given in the question. Based on those given information's the answer can be easily deduced. 

Number of cups that a coffee pot makes in 1 1/2 minutes = 6 cups
Number of cups that a coffee pot makes in 3/2 minutes = 6 cups
Then
Number of cups that a coffee pot makes in 1 minute = 6/(3/2) cups
                                                                                   = 12/3 cups
                                                                                   = 4 cups.

I hope that the procedure is clear enough for you to understand.

The second and fourth answer are correct