A semicircular piece of paper (with radius 7 cm) is folded along the diameter to form a cone such that he centre of the semicircle becomes the vertex of the cone.If the base of the cone is covered by a circular paper lid, what is the total surface area of the cone ?

If shortest side of a right angled triangle was 5 cm longer and the longest side was 5 cm shorter, the triangle would be equilateral.  What is the area of the original right angled triangle?

An experiment succeeds twice as often as it fails. What is the probability that in the next 5 trials there will be four successes?