- You could...in this case plugging in n = 12 eliminates all choices except C. A better way (e.g. if you don't have answer choices) is to notice that the interval (11 7/8, 12 1/8) contains all numbers within 1/8 distance of 12 and your desired interval is |n-12| < 1/8.
- He keeps 2k/3 dollars each day, the number of days required is 1000/(2k/3) = 3000/2k = 1500/k. You can also solve by plugging in a number for k, e.g. k = 3.
- Assume Esther took 2t hours driving to work, then she took 3t time driving home (using D = rt). Then 2t+3t = 1 (hour) --> t = 1/5 hr. So 2t = 2/5 hr, and she drove (45 mph)(2/5 hr) = 18 mi to work.
- n packages on Mon., 4n packages on Tues., n+3 packages on Wed.
Arithmetic mean = (n + 4n + n+3)/3 = 2n+1