请问,假设题目为“A call center receives an average of two phone calls per hour. The probability that they will receive 4 calls in an 4-hour day is closest to”,课堂上的做法是是将hazard rate调整为每4小时平均有8个来电,再做计算,那为什么不能将在“4小时里接到4个来电”变换为“1小时接到1个来电”,然后用原始的hazard rate(1小时平均2个来电)做计算呢?