In a examination paper of five questions 5% of the candidates answered all the questions and 5% none. Of the rest 25% none. Of the rest 25% answered four. If 24 1/2% of the entire number answered only two questions and 200 answered only three questions, how many candidates competed?
A specific mass of pure water is frozen to form completely transparent ice, in the shape of a lens. When force underwater, the lens diverges light, What is the shape of the lens
