Recent Statistical problem that occurred at my job facility.
Fleet consists out of 32 trains each needs to get radio communication equipment upgrade. During testing period approximately every 4th devices came defective from factory due to limited production and tight schedule. And by contract company has to keep 20% extra devices as spare parts. Question was given that 40 radio devices were purchased is it enough to convert whole fleet of 32 vehicles during next testing phase, accounting for possible defects from factory?
Komron Zokhidov