问几个GWD数学

1，

Is ½x½< 1?

(1)   ½x + 1½ = 2½x - 1½

(2) ½x - 3½
   ≠ 0

答案C

2，

On a certain transatlantic crossing, 20 percent of a ship’s passengers held round-trip tickets and also took their cars abroad the ship.  If 60 percent of the passengers with round-trip tickets did not take their cars abroad the ship, what percent of the ship’s passengers held round-trip tickets?

 A.    33 1/3%

B.     40%

C.     50%

D.    60%

E.     66 2/3%

答案C

A box contains 10 light bulbs, fewer than half of which are defective.  Two bulbs are to be drawn simultaneously from the box.  If n of the bulbs in box are defective, what is the value of n?
(1) The probability that the two bulbs to be drawn will be defective is 1/15.
(2)  The probability that one of the bulbs to be drawn will be defective and the other will not be defective is 7/15.

选D 这题2）我怎么算不得这答案

请教下这3题，~~~~谢谢