Some electronic devices are better used than new: the failure rate is higher when they are new than when they are six months old
. For example, half of the personal music players of a particular brand have a flaw. Of the player has the flaw, it dies in the first two months with a probability of 30%, in the first four months with a probability of 70%, and in the first six months with a probability of 100%. If the player DOES NOT have the flaw, however, it dies in the first two months with a probability of 0%, in the first four months with a probability of 5%, and in the first six months with a probability of 10%. The probability that it has the flaw is ____.
Given that half of the personal music players sold by a particular brand have a flaw. If the player has the flaw, it dies in the first six months. If it does not have this flaw, then only 20% fail in the first six months. Let A be the event that it fails in I 6 months B1 = it has a flaw B2 = it does not have a flaw B1 and B2 are mutually exclusive and exhaustive the chances that it has this flaw =The probability that it has the flaw is
(x-9)²=-3+x expand x²-18x+81=-3+x minus x both sides and add 3 x²-19x+84=0 factor what 2 numbers multiply to get 84 and add to get -19? -7 and -12 (x-7)(x-12)=0
