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GMAT Probability Questions
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05 Feb 2019, 06:02
GMAT Probability Practice Questions PROBLEM SOLVING If the probability of rain on any given day in City X is 50 percent, what is the probability that it rains on exactly 3 days in a 5day period? (A) 8/125 (B) 2/25 (C) 5/16 (D) 8/25 (E) 3/4 Answer, Explanation, and Timer Stats are hereIf a certain coin is flipped, the probability that the coin will land heads is 1/2. If the coin is flipped 5 times, what is the probability that it will land heads up on the first 3 flips and not on the last 2 flips?A. 3/5 B. 1/2 C. 1/5 D. 1/8 E. 1/32 Answer, Explanation, and Timer Stats are hereThe probability is 1/2 that a certain coin will turn up heads on any given toss. If the coin is to be tossed three times, what is the probability that on at least one of the tosses the coin will turn up tails?(A) 1/8 (B) 1/2 (C) 3/4 (D) 7/8 (E) 15/16 Answer, Explanation, and Timer Stats are hereA fair coin is tossed 4 times. What is the probability of getting at least 2 tails?A. 1/16 B. 1/2 C. 3/16 D. 11/16 E. 3/8 Answer, Explanation, and Timer Stats are hereA small company employs 3 men and 5 women. If a team of 4 employees is to be randomly selected to organize the company retreat, what is the probability that the team will have exactly 2 women? A. 1/14 B. 1/7 C. 2/7 D. 3/7 E. 1/2 Answer, Explanation, and Timer Stats are hereAn integer n between 1 and 99, inclusive, is to be chosen at random. What is the probability that n(n+1) will be divisible by 3 ?A. 1/9 B. 1/3 C. 1/2 D. 2/3 E. 5/6 Answer, Explanation, and Timer Stats are hereTwo dice are tossed once. The probability of getting an even number at the first die or a total of 8 isA. 1/36 B. 3/36 C. 11/36 D. 20/36 E. 23/36 Answer, Explanation, and Timer Stats are hereA fair coin is tossed 5 times. What is the probability of getting at least three heads on consecutive tosses?A. 2/16 B. 1/4 C. 7/24 D. 5/16 E. 15/32 Answer, Explanation, and Timer Stats are hereTanya prepared 4 different letters to be sent to 4 different addresses. For each letter, she prepared an envelope with its correct address. If the 4 letters are to be put into the 4 envelopes at random, what is the probability that only 1 letter will be put into the envelope with its correct address?A. 1/24 B. 1/8 C. 1/4 D. 1/3 E. 3/8 Answer, Explanation, and Timer Stats are hereDATA SUFFICIENCY Each of the marbles in a jar is either red or white or blue. If one marble is to be selected at random from the jar, what is the probability that the marble will be blue?(1) There are a total of 24 marbles in the jar, 8 of which are red. (2) The probability that the marble selected will be white is 1/2. Answer, Explanation, and Timer Stats are hereIn a certain class, one student is to be selected at random to read. What is the probability that a boy will read?(1) Twothirds of the students in the class are boys. (2) Ten of the students in the class are girls. Discussed Answer, Explanation, and Timer Stats are hereA jar contains 30 marbles, of which 20 are red and 10 are blue. If 9 of the marbles are removed, how many of the marbles left in the jar are red?(1) Of the marbles removed, the ratio of the number of red ones to the number of blue ones is 2:1. (2) Of the first 6 marbles removed, 4 are red. Answer, Explanation, and Timer Stats are hereWhat is the probability that a student randomly selected from a class of 60 students will be a male who has brown hair?(1) Onehalf of the students have brown hair. (2) Onethird of the students are males. Answer, Explanation, and Timer Stats are hereA 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. Answer, Explanation, and Timer Stats are hereTerry holds 12 cards, each of which is red, white, green, or blue. If a person is to select a card randomly from the cards Terry is holding, is the probability less than 1/2 that the card selected will be either red or white?(1) The probability that the person will select a blue card is 1/3 (2) The probability that the person will select a red card is 1/6 Answer, Explanation, and Timer Stats are hereEach of the 25 balls in a certain box is either red, blue or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it? (1) The probability that the ball will both be white and have an even number painted on it is 0 (2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2 Answer, Explanation, and Timer Stats are hereA jar contains 8 red marbles and y white marbles. If Joan takes 2 random marbles from the jar, is it more likely that she will have 2 red marbles than that she will have one marble of each color?(1) y ≤ 8 (2) y ≥ 4 Answer, Explanation, and Timer Stats are hereA drawer contains 8 socks, and 2 socks are selected at random without replacement. What is the probability that both socks are black?(1) The probability is less than 0.2 that the first sock is black. (2) The probability is more than 0.8 that the first sock is white. Answer, Explanation, and Timer Stats are here
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