The L.C.M and H.C.F of the two numbers are 84 and 21 respectively. If the numbers have a ratio of 1: 4, what is the larger number?

To cover a certain distance with a speed of 60 km/hr, a train takes 15 hours. If covers the same distance in 12 hours, what will be its speed?

A pipe can fill a tank in x hours and an another can empty it in y hours. In how many hours will they together fill it. If y>x?

75% of a number is equal to three-seventh of another number. What is the ratio between the first number and the second number respectively?

The pipe can fill a tank in 36 minutes and the another pipe can empty it in 45 minutes. If both pipes are opened simultaneously, the time (in hours) it takes to fill half the capacity of the tank is:

AB is diameter of a circle with centre 'O'. CD is a chord which is equal to the radius of the circle. AC and BD are extended so that they intersect each other at point P. Then find the value of ∠ APB.

If secθ + tanθ = 3, then the value of secθ is:

If radius of a sphere is decreased by 48%, then by what percent does its surface area decrease?