Final answer:
The crash cost per period is $400 per day.
Step-by-step explanation:
The crash cost per period can be calculated by taking the difference in costs between the normal duration and the shortened duration, and dividing it by the difference in durations. In this case, the difference in costs is $2,000 and the difference in durations is 15 - 10 = 5 days. So, the crash cost per period is $2,000 / 5 = $400 per day.