GMAT Sample Questions

Quantitative Section : GMAT Sample Problem Solving Ability

Probability

211. A number is selected at random from first thirty natural numbers. What is the chance that it is a multiple of either 3 or 13?
     1. 17/30
     2. 2/5
     3. 11/30
     4. 4/15

     Ans : B

212. What is the probability of getting at least one six in a single throw of three unbiased dice?
     1. 1 / 6
     2. 125 / 216
     3. 1 / 36
     4. 91 / 216

     Ans : D

213. What is the probability that a two digit number selected at random will be a multiple of '3' and not a multiple of '5'?
     1. 2 / 15
     2. 4 / 15
     3. 1 / 15
     4. 4 / 90

     Ans : B

214. A man bets on number 16 on a roulette wheel 14 times and losses each time. On the 15th span he does a quick calculation and finds out that the number 12 had appeared twice in the 14 spans and is therefore, unable to decide whether to bet on 16 or 12 in the 15th span. Which will give him the best chance and what are the odds of winning on the bet that he takes? (Roulette has numbers 1 to 36)
     1. 16; 22 : 14
     2. 12; 72 : 1
     3. 12; 7 : 1
     4. Either; 35 : 1

     Ans : D

215. Two squares are chosen at random on a chessboard. What is the probability that they have a side in common?
     1. 1 / 18
     2. 64 / 4032
     3. 63 / 64
     4. 1 / 9

     Ans : A

216. When two dice are thrown simultaneously, what is the probability that the sum of the two numbers that turn up is less than 11?
     1. 5 / 6
     2. 11 / 12
     3. 1 / 6
     4. 1 / 12

     Ans : B

217. When 4 dice are thrown, what is the probability that the same number appears on each of them?
     1. 1/36
     2. 1/18
     3. 1/216
     4. 1/5

     Ans : C

218. An experiment succeeds twice as often as it fails. What is the probability that in the next 5 trials there will be four successes?
     1. 0
     2. (2/3)^4
     3. 5*((2/3)^4)*(1/3)
     4. ((2/3)^4)*(1/3)

     Ans : C

219. An anti aircraft gun can fire four shots at a time. If the probabilities of the first, second, third and the last shot hitting the enemy aircraft are 0.7, 0.6, 0.5 and 0.4, what is the probability that four shots aimed at an enemy aircraft will bring the aircraft down?
     1. 0.084
     2. 0.916
     3. 0.036
     4. 0.964

     Ans : A

220. A can complete a project in 20 days and B can complete the same project in 30 days. If A and B start working on the project together and A quits 10 days before the project is completed, in how many days will the project be completed?
     1. 18 days
     2. 27 days
     3. 26.67 days
     4. 16 days

     Ans : A