A machine, working at a constant rate, manufactures 72 staplers in 28 minutes. How many staplers does it make in 1 hr 52 min?  Choose the correct choice: A) 268 B) 262 C) 300 D) 288 E) 250

Rationale: "change 1 hr 52 min to 112 min . for this , we need to set up a simple proportion of staplers per time 72 / 28 = s / 112 . the absolutely worst thing you could do at this point in the problem is to cross - multiply . that would be a supremely unstrategic move . we can cancel the common factor of 28 in the two denominators . 72 / 28 * 28 = s / 112 * 28 72 / 1 = s / 4 s = 4 * 72 s = 288 the machine would be 288 staplers in 1 hr 52 min . answer : d"
Answer: D