Assume that the store stocks 30 percent brand A, 30 percent brand B, and the rest are brand X. Assume further that 15 percent of brand A, 20 percent of brand B, and 30 percent of brand X will not provide the number of pages advertised. A customer buys a cartridge at random.

If the customer returns the cartridge because it does not provide the number of pages advertised, what is the probability that the cartridge was brand X