11.If X folloes a binomial distribution with parameters n and p, 0 < p < 1. If P(X = r)/P(X = n - r) is independent of n and r, then value of p is

12.In a single throw of two dice, the probability of obtaining a total of 7 or 9, is

13.The total area under a standard normal curve is

14.The probability that a leap year selected at random will contain 53 Sundays, is

15.The odds in favour of throwing at least 8 in a single throw with two dice, are