Question 710631
  first variety :  portion of water  =  1/4   (since ratio = 1:3   total 4 parts) 
second  variety :  portion of water  =  1/6   (since ratio = 1:5   total 6 parts)
  mix  :  portion of   water  = 1/5   (since ratio = 1:4   total 5 parts)
             
                 1/4                             1/6
          

                                  1/5
  proportion of first variety  =  (1/5 - 1/6 )  =   1/30
   proportion of first variety  =  (1/4 - 1/5 )  =   1/20
 ratio in which first variety and second variety  to be mixed  = 1/30 : 1/20 
                                                               =2:3
  total volume of the mix  = 30 lbs
   volume of the first variety int  the mix  =   2/5 *(30 )
                             =12 lbs
 volume of the second variety int  the mix   =  3/5 * 30
                                              = 18 lbs