If 81 : y :: y : 196, find the positive value of y.

The mean proportional between 25 and a number N is two times the mean proportional between 15 and 35.

The mean proportional of 0.5 and 72 is:

The mean proportional between 36 and a number N is three times the mean proportional between 8 and 32. The number N is:

Find the mean proportion of 5.76 and 0.88. (rounded off to two decimal places)

If 36 : y :: y : 9, find the positive value of y.

Find the mean proportional between 24 and 150.

The mean proportional between 9 + $$3\sqrt{7}$$ and 18 – $$6\sqrt{7}$$ is:​

The mean proportional between 0.09 and 16 is:

The mean proportional between $$\left(9 + 4\sqrt{5}\right) \text{ and } \left(18 - 8\sqrt{5}\right) \text{ is:}$$​