The probability that randomly selected calculator from a store is of brand r is proportional to r, r
Channel: Doubtnut
Date: 17/05/2020

The probability that randomly selected calculator from a store is of brand r is proportional to r, r=1,2,..,6. Further, the probability of a calucltor of brand r being defective is `(7-r )/(21), r=1,2,..,6`. Then the probability that a calculator randomly selected from the store being defective is