Muhammad and Hayley deposit some amount in joint back account such that total balance remains 600. If amount deposited by Muhammad and Hayley are plotted as linear graph on x-y plane, find the area between this graph and coordinate axes.

A cone made completely of metal (i.e. it is not hollow) has a base radius of 7 cm, and height of 28 cm. If we melt it and recast it into a sphere, what will be the radius of sphere?

Ethan's age is twice that of Chloe, Chloe's age is twice that of Caleb and Caleb's age is twice that of Cayden. If the average of the ages of Ethan, Chloe, Caleb and Cayden is 15 years, then what is the present age of Ethan?