Adding up the frequency column, we get 31 (an odd number). Thus, the median of the entire set is the middle element, and there are 15 temperature measurements on each side of the median (31). 15 being an odd number is the reason that the median of the first 15 numbers is the 7th member. In other words, the first quartile is the 7th member of the entire set, which includes temperatures 50-59 and 60-69. The first quartile would include 5 measurerments in the 50-59 range and two measurements in the 60-69 range. Thus, the "lower quartile median" (which is the 1st quartile) is in the interval 60-69 (answer)