Probability Questions (959)

Since \(A\), \(B\), \(C\) are mutually exclusive events with \(P(A) = \frac{3x+1}{3}\), \(P(B) = \frac{1-x}{4}\) and \(P(C) = \frac{1-2x}{2}\), the range of \(x\) such that all probabilities are valid is:
In a random experiment, a fair die is rolled until two fours are obtained in succession. The probability that the experiment will end in the fifth throw of the die is equal to:
For Problems 7–9: A JEE aspirant estimates that she will be successful with an 80% chance if she studies 10 hours per day, with a 60% chance if she studies 7 hours per day, and with a 40% chance if she studies 4 hours per day. She further believes that she will study 10 hours, 7 hours, and 4 hours per day with probabilities 0.1, 0.2, and 0.7, respectively.Given that she is successful, the chance that she studied for 4 hours is
A fair coin is tossed 10 times. Then the probability that two heads do not occur consecutively is
A box contains tickets numbered $1$ to $N$ is tickets are drawn from the box with replacement. The probability that the largest number on the tickets is $k$, is
In throwing a dice thrice, getting numbers in order denoted by \(a, b, c\), satisfying \(a^2 + 4b^2 + 4c^2 - 2ab - 4bc - 2ac = 0\). If probability such that point \((a, b, c)\) lies inside the tetrahedron formed by the plane \(x + y + z = 10\) and co-ordinate planes is \(\dfrac{6}{\lambda}\), where \(\lambda \in N\), then \(\lambda\) is:
2 coins can be both 10 rupee coin, both 5 rupee coins or one 5 rupee coin and one 11 rupee coin. Expected value = $\frac{20}{1} + \frac{x}{10} + \frac{20+25}{3} = 15$.
Class XII has sections A (40%) and B (60%). 20% students get into IIT. $P$(IIT from A)$=5P$(IIT from B). A student not selected in IIT is chosen. Probability he is from section B is
The probability that a rectangle picked up from a chessboard has the area 6 cm² where the distance between consecutive parallel lines on the board is 1 cm, is
The probability of \(A\) occurring is 0.5 and of \(B\) occurring is 0.3. If \(A\) and \(B\) are mutually exclusive events then the probability of neither \(A\) nor \(B\) occurring is
If the probability for \(A\) to fail in an examination is 0.2 and that for \(B\) is 0.3 then the probability that either \(A\) or \(B\) fails is 0.5.
In a multiple choice question, there are four alternative answers of which one or more than one is correct. A candidate will get marks on the question only if he ticks the correct answer. The candidate decides to tick answers at random. If he is allowed up to three chances to answer the question, then find the probability that he will get marks on it.
Let \(X\) be the random variable which denotes the ₹ gained by a person. Two dice are thrown. The person gets ₹15 if same numbers appear on both dice, ₹12 if the sum is 9, and loses ₹6 otherwise. The expected gain/loss \(E(X)\) is:
Two cards are drawn successively with replacement from a well-shuffled deck of 52 cards. Let X denote the random variable of number of aces obtained in the two drawn cards. Then \(P(X = 1) + P(X = 2)\) equals:
A bag contains 20 coins. If the probability that bag contains exactly 4 biased coin is 1/3 and that of exactly 5 biased coin is 2/3, then the probability that all the biased coin are sorted out from the bag in exactly 10 draws is
A candidate attempts 50 problems. The probability of solving any problem is \(\dfrac{4}{5}\). What is the probability that the candidate is unable to solve less than two problems (i.e., is able to solve either 50 or 49 problems)?
A card from a pack of 52 cards is lost. From the remaining cards, two cards are drawn and are found to be spades. Find the probability that missing card is also a spade.
An unbiased ordinary dice is rolled four times. Out of the four face-values obtained, the probability that the minimum face-value is not less than 2 and the maximum face-value is not greater than 5, is
The probability that a random chosen three-digit number has exactly 3 factors is
Three coins are tossed. If one of them shows tail, then find the probability that all three coins show tail.
For Problems 13–15: An amoeba either splits into two or remains the same or eventually dies out immediately after completion of every second with probabilities, respectively, 1/2, 1/4, and 1/4. Let the initial amoeba be called as mother amoeba and after every second, the amoeba, if it is distinct from the previous one, be called as 2nd, 3rd, ... generations.The probability that immediately after completion of 2 s all the amoeba population dies out is
The sum of two positive quantities is equal to 2n. Find the probability that their product is not less than 3/4 times their greatest product.
\(P(X = Y)\) is
In a poker game what is the probability of getting a "pair" in five cards? [A pair consists of 2 cards of the same kind (e.g., 2 Kings) and 3 cards that are different from the kind of the pair (e.g., different from Kings) and that are all different from each other.]
The probability that the wife will be alive 10 years hence is \(\frac{7}{15}\) and that of the husband is \(\frac{7}{10}\). What is the probability that at least one of them will be alive 10 years hence?
\(\displaystyle e^{\lim_{x \to 0} 2\left(\dfrac{a^x - 1 + b^x - 1}{2}\right)} = e^{\ln ab} = ab = 6\). The value of \(P(E)\) where ordered pairs \((a,b)\) with \(ab = 6\) are selected from \(\{(1,6),(6,1),(2,3),(3,2)\}\) is:
A coin is tossed three times. Let \(A\): at least two heads, \(B\): at most two heads. Find \(P(A/B)\).
A card is drawn at random from a pack of cards. What is the probability that the drawn card is neither a heart nor a king?
Let p, q be chosen one by one from the set \(\{1, \sqrt{2}, \sqrt{3}, 2, e, \pi\}\) with replacement. Now a circle is drawn taking (p, q) as its centre. Then the probability that at the most two rational points exist on the circle is (rational points are those points whose both the coordinates are rational)
A fair die is thrown 20 times. The probability that on the 10th throw, the fourth six appears is
Five horses are in a race. Mr. A selects two of the horses at random and bets on them. The probability that Mr. A selected the winning horse is
A player \(X\) has a biased coin whose probability of showing heads is \(p\) and a player \(Y\) has a fair coin. They start playing a game with their own coins and play alternately. The player who throws a head first is a winner. If \(X\) starts the game, and the probability of winning the game by both the players is equal, then the value of '\(p\)' is
If two events \(A\) and \(B\) are such that \(P(A') = 0.3\), \(P(B) = 0.4\) and \(P(A \cap B') = 0.5\), then find the value of \(P[B/(A \cup B')]\).
If $\frac{1-p}{p}, \frac{1-q}{q}$ and $\frac{1-r}{r}$ are probabilities of mutually exclusive events of a random experiment, then the range of $p$ is
Find the probability that a leap year will have 53 Fridays or 53 Saturdays.
A man alternately tosses a coin and throws a die beginning with the coin. The probability that he gets a head in the coin before he gets a 5 or 6 in the dice is
If ten objects are distributed at random among ten persons, find the probability that at least one of them will not get any object.
The chances of defective screws in three boxes \(A\), \(B\), \(C\) are 1/5, 1/6, 1/7, respectively. A box is selected at random and a screw drawn from it at random is found to be defective. Then find the probability that it came from box \(A\).
Let a random variable \(X\) have a binomial distribution with mean 8 and variance 4. If \(P(X \leq 2) = k/2^{16}\), then \(k\) is equal to __________.
Cards are drawn one by one without replacement from a pack of 52 cards. The probability that 10 cards will precede the first ace is
The probability that an event \(A\) happens in one trial of an experiment is 0.4. Three independent trials of the experiment are performed. The probability that the event \(A\) happens at least once is
An unbiased dice, with faces numbered 1, 2, 3, 4, 5, 6, is thrown \(n\) times and the list of \(n\) numbers shown up is noted. Then find the probability that among the numbers 1, 2, 3, 4, 5, 6 only three numbers appear in this list and each number appears at least once.
An urn contains 5 red and 2 green balls. A ball is drawn at random from the urn. If the drawn ball is green, then a red ball is added to the urn and if the drawn ball is red, then a green ball is added to the urn; the original ball is not returned to the urn. Now, a second ball is drawn at random from it. The probability that the second ball is red, is __________ (up to four decimal places).
Three critics review a book. Odds in favor of the book are 5:2, 4:3, and 3:4, respectively, for the three critics. The probability that majority are in favor of the book is
A class consists of 80 students, 25 of them are girls and 55 are boys. If 10 of them are rich and the remaining are poor and also 20 of them are intelligent, then the probability of selecting an intelligent rich girl is
$A$ speaks truth in 60\% cases and $B$ speaks truth in 70\% cases. The probability that they will say the same thing while describing single event is:
Let \(A\) and \(B\) be two events such that \(P(A \cap B') = 0.20\), \(P(A' \cap B) = 0.15\), \(P(A' \cap B') = 0.1\), then \(P(A/B)\) is equal to
A multiple choice examination has 5 questions. Each question has three alternative answers of which exactly one is correct. The probability that a student will get 4 or more correct answers just by guessing is
Three factories A, B and C produce the same product. The factory A produces twice as many as B produces while the factories B and C produce in the same quantity. It is known that 2% of the products of A as well as C are defective while 4% of the products of B are defective. All the products of the three factories are stocked together. If a product is selected at random from the stock, what is the probability that the product is defective?
An unbiased coin is tossed. If the outcome is a head then a pair of unbiased dice is rolled and the sum of the numbers obtained on them is noted. If the toss of the coin results in tail then a card from a well-shuffled pack of nine cards numbered 1, 2, 3, …, 9 is randomly picked and the number on the card is noted. The probability that the noted number is either 7 or 8 is: