doldrums Posted October 18, 2005 Share Posted October 18, 2005 The OAs are given below, but I am doubtful on their veracity. Please help verify the correct answers and the reasonings. 1. 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. 2. If positive integer x is a multiple of 6 and positive integer y is a multiple of 14, is xy a multiple of 105? (1) x is a multiple of 9. (2) y is a multiple of 25. 3. 150, 200, 250, n Which of the following could be the median of the 4 integers listed above? I. 175 II. 215 III. 235 A. I only B. II only C. I and II only D. II and III only E. I, II, and III OA: D, B, C I got: A, E, A Quote Link to comment Share on other sites More sharing options...
chix475ntu Posted October 18, 2005 Share Posted October 18, 2005 Agree with all the OAs. here are the explanations. 1. 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. ==> n/10 * (n-1)/9 = 1/15 ==> n=3 (2) The probability that one of the bulbs to be drawn will be defective and the other will not be defective is 7/15. (10-n)/10 * n/9 * 2 = 7/15 ==> n=3 D 2. If positive integer x is a multiple of 6 and positive integer y is a multiple of 14, is xy a multiple of 105? 105 = 3 * 5 * 7 .. so we need to check whether x or y is a multiple of 5 or not. (1) x is a multiple of 9. insufficient (2) y is a multiple of 25. sufficient B 3. 150, 200, 250, n Which of the following could be the median of the 4 integers listed above? the range of the medain will be 175 so I & II C Quote Link to comment Share on other sites More sharing options...
doldrums Posted October 18, 2005 Author Share Posted October 18, 2005 So as I suspected, I think statement II of Question3 has a typo. It should read "225" as opposed to "215" Hence I chose A Quote Link to comment Share on other sites More sharing options...
Ankost Posted October 18, 2005 Share Posted October 18, 2005 3. If n is less than 150, the median will be 175. If n=230, the median will be 215. If n>250, the median will be 225. The median can not be more than 225 and less than 175. Quote Link to comment Share on other sites More sharing options...
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