The ages, in months, of 15 cars on a forecourt are listed below in order.
3, 5, 6, 8, 8, 9, 11, 12, 14, 15, 17, 18, 20, 23, 293,\ 5,\ 6,\ 8,\ 8,\ 9,\ 11,\ 12,\ 14,\ 15,\ 17,\ 18,\ 20,\ 23,\ 293, 5, 6, 8, 8, 9, 11, 12, 14, 15, 17, 18, 20, 23, 29
Find the median, the lower quartile and the upper quartile of these ages.