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In a box of 10 electric bulbs, 2 are defective. Two bulbs are selected at random one after the other from the box. The first bulb after selection being put back in the box before making the second selection. The probability that both the bulbs are without defect is (a) \(9 / 25\) (c) \(4 / 5\) (b) \(16 / 25\) (d) \(8 / 25\)

A box contains 6 nails and 10 nuts. Half of the nails and half of the nuts are rusted. If one item is chosen at random, what is the probability that it is rusted or is a nail? (a) \(3 / 16\) (c) \(11 / 16\) (b) \(5 / 16\) (d) \(14 / 16\)

There are four machines and it is known that exactly two of them are faulty. They are tested, one by one, in a random order till both the faulty machines are identified. Then the probability that only two tests are needed is (a) \(1 / 3\) (b) \(1 / 6\) (c) \(1 / 2\) (d) \(1 / 4\)