If a : b =4 : 5, b: c=20 : 11 and c:d =6 : 7, then value of a : b : c : d will be

Direction: In the following question, out of the four alternatives, choose the one which can be substituted for the given sentence.

Select the letter that will come next in the following series.
O, R, U, X, A, ___

A and B can separately complete a piece of work in 20 days and 30 days respectively. They worked together for some time then B left the work. If A completed the rest of the work in 10 days, then B worked for how many days?

Which organization has successfully conducted final trial of Nag anti-tank guided missile?

The total surface area of a solid right circular cylinder is twice that of a solid sphere. If they have the same radii, the ratio of the volume of the cylinder to that of the sphere is given by