The top three winners of the local origami folding contest are Ashley, Beatrice, and Christopher. Veteran origamian Ashley can fold 100 paper cranes in 5 minutes. New-comers Beatrice and Christopher can both fold 100 cranes in 6 minutes.Together they will represent their school at the State contest. They will work as a team to compete in the event where they have to fold 480 paper cranes in the least amount of time. Assuming their speed of folding paper cranes does not change at all. How long does it take?
Together they fold 100/5 + 100/6 = (600+500)/30 = 1100/30 cranes per minute
480 cranes / (1100/30 cranes / minute) = 480 * 30 /1100 = ~ 13 minutes