The ratio of the third proportional to 12 and 30 and the mean proportional between 9 and 25 is:

तीसरा समानुपाती (c) = b^2/a = 30*30/12 = 75। माध्य समानुपाती (x) = sqrt(a*b) = sqrt(9*25) = 15। अनुपात = 75 : 15 = 5 : 1।