Mr. McNeely takes a register of the total number of students present in class every day. On a particular week, the number of students in the class on the second day was 40 more than the first day. The number of students who didn't turn up for the class on the second day was twice the number of students who didn't turn up on the third day. On the third day, 1/7 of the total number of students of the class called in sick. If the total number of students in the class is 280, calculate the number of absent students in the three days. Let's answer step by step:
On the third day, 1 / 7 * 280 = 40 students called in sick. If the number of students absent on the second day was twice the number on the third day, then 2 * 40 = 80 students didn't show up for the class on the second day. The total number of students present in the class on the second day was 280 - 80 = 200. If 40 fewer students showed up for the class on the first day than on the second day, then 200 - 40 = 160 students showed up for the class on the first day. The number of students absent on the first day is 280 - 160 = 120. In the three days, the total number of absentees is 120 + 80 + 40 = 240. The answer: 240.