1. The first term, a1, in an arithmetic sequence is 8; the fourth term, a4, is 6. How many terms must be added to have the sum, Sn, of the terms equal 42?
2. Two terms of an arithmetic sequence are 19 and 95. The common difference, d, between consecutive terms is a positive integer such that 1 < d < 76. How many possible values can d have?
3. In September, 60% of students in a class knew their multiplication facts. By December, 70% of students knew them. Assuming that students do not forget what they learned, what percentage of the students who did not know their facts in September learned them by December?
4. When is the first time after 4:00 that the minute hand is exactly 2 minutes (2/60 of a complete rotation) past the hour hand?