Express 31 billion in scientific notation

Which of the following three dimensional figures has a circle as it’s base

Johnny rode his bike to a friends house 4 blocks down the street in his neighborhood. he immediately rode back home once he realized his friend was unable to play. what was his displacement for the total bike ride trip? what could you use as a reference point ? show the steps to solve this problem.

The random variable x is defined as the number marking the sector in which the arrow lands when the spinner in the diagram is spun once.