To estimate the mean number of days in the hospital for a motorcyclist involved in a crash without a helmet, a sample of 40 such motorcyclists is taken. Match the following: - mean time spent in the hospital for all motorcyclists involved in a crash without a helmet - all motorcyclists involved in a crash without a helmet - 40 motorcyclists involved in a crash without a helmet - a motorcyclist involved in a crash without a helmet - mean time spent in the hospital for 40 motorcyclists involved in a crash without a helmet - time spent in the hospital statistic population individual parameter variable sample