Winners from last weeks math problem, and the new problem of the week

The Cullinan Diamond Problem

Answer:  65.6% Winner: Maddy Johnson

Rockin' Roller Coaster
While the earliest roller coasters date back to the 17th and 18th century, it was not until January 20, 1885 that inventor LeMarcus Adna Thompson patented the roller coaster. The duration of a ride on the Rockin’ Roller Coaster (RCC)  is 1 minute 30 seconds. The RCC has only one train  consisting of a series of linked cars, each of which carries a pair of passengers. It takes each group of passengers exactly 30 seconds to board the train and exactly 30 seconds to exit the train. In one hour, 480 people board the train, complete the ride and exit the train. Assuming there is never a seat left vacant, how many linked cars are in the RCC’s train?