The first task in such exercises is to order the data in ascending order. 201,218, 242, 257, 265, 275, 301. The algorithm to find the first quartile of a distribution of discrete observations is: If the number of observations is odd; Exclude the median. Then, the first quartile is the median of the lower half of the observations. If the number of observations is even, take the median of the lower half of observations immediately. Here, we have 7 observations. The median is 257 and the observations below it are 201,218,242. The median of this is 218. Thus, 218 is the first quartile. (Similarly, 275 is the 3rd quartile).
