Question

the fourth proportional of 5,6 and 7 correct to two places of decimal

Answer 1

Fourth proportional of 5, 6 and seven is solved as follows:

5, 6 , 7, x .....we are trying to find x

( and since these numbers are proportional, we can cross multiply and equate the means of ratios formed by the first pair and the last pair.)

5:6 = 7:x    that is  5/6 = 7/x  (apply means-extremes property of                                                                proportions)  5(x)= 7(6)
     therefore 5x=42
                      x= 42/5
                      
                      x= 8.4
Therefore the fourth proportional to 2 decimal places = 8.40