C.P of a unit quantity of 1st kind  = Rs. 62
C.P of a unit quantity of 2nd kind  = Rs. 72
Mean price = Rs. 64.50

C.P of unit quantity         C.P of unit quantity

of 1st kind                         of 2nd kind

    (Rs. 62)                             (Rs. 72)

                     \                       /
                        Mean Price

                         (Rs. 64.50)

                    /                        \

     (72 – 64.50)          :           (64.50 – 62)

       7.50                                      2.50
Required ratio = 7.50 : 2.50 = 3 : 1

Hence, option 1 is the correct answer.