If the mean of the first n natural number is 15, then find n.

ABC and BDE are two equilateral triangles such the D is the mid-point of BC. Ratio of the areas of triangles ABC and ADE is____.

A die is thrown once. What is probability of getting a number less than 3?

OR

If the probability of winning a game is 0.07, what is the probability of losing it?

Two cones have their heights in the ratio 1 : 3 and radii in the ratio 3 : 1. What is the ratio of their volumes?

Find the angle of elevation of the sun at that moment?

The ratio of the length of a vertical rod and the length of its shadow is .