A bag contains n + 1 coins. It is known that one of these coins shows heads on both sides, whereas the other coins are fair. One coin is selected at random and tossed. If the probability that toss results in heads is 7/12, then the value of n is


Correct option is


Let E1, denote the event a coin with two heads is selected and E2, denote the event a fair coin is selected. Let A be the event the toss results in heads. Then



⇒           12 + 6n = 7n + 7   ⇒   n = 5.



Let abcd be four integers such that ad is odd and bc is even, then ax3bx2 + cx + d = 0       ... (1)      



A bag contains 2 Black, 4 white and 3 Red balls. One ball is drawn at random and kept aside. Then another ball is drawn and is also kept aside. This process is continued till all are drawn. Find the probability that the balls drawn are in the sequence 2 Black, 4 white and 3Red


If X follows a binomial distribution with parameters n = 100, p = 1/3, then P(X = r) is maximum when r =


A team of 8 couples, (husband and wife) attend a lucky draw in which 4 persons picked up for a prize. Then, the probability that there is at least one couple is


An unbiased die with faces marked 1, 2, 3, 4, 5 and 6 is rolled four times. Out of 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


If X following a binomial distribution with parameters n = 8 and p = 1/2, then  equals


Two numbers b and c are chosen at random with replacement from the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9. The probability that x2 + bx + c > 0 for all x Ïµ R is


India plays two matches each with west indies and Australia. In any one match, the probabilities of India getting points 0, 1, 2 are respectively 0.45, 0.05 and 0.05 and 0.50 for base drawn and won. Assuming that the outcomes are independent, the probability of India getting at least 7 points is


If two events A and B are such that P(AC) = 0.3, P(B) = 0.4 and P(ABC) = 0.5 then P(B/A  BC) =


In a game, a person is paid Rs. 5 if he gets all heats or all tails when three coin are tossed, and he will pay Rs. 3 if either one or two heads shown. What can be expect to win on the average per game?