Chapter 20

The probability that a leap year selected at random contains either 53 Sundays or 53 Mondays, is : (a) $\frac{17}{53}$ (b) $\frac{1}{53}$ (c) $\frac{3}{7}$ (d) none of these

In order to get atleast once a head with probability $P\ge 0.9$, the number of times a coin needs to be tossed is : (a) 3 (b) 2 (c) 5 (d) 4

Out of 13 applicants for a job, there are $5\mathrm{w}$ na 8 men, It is desired to select 2 persons for the job. The probability that atleast one of the selected persons will be a woman is: (a) $\frac{25}{39}$ (b) $\frac{31}{65}$ (c) $\frac{25}{69}$ (d) $\frac{5}{13}$

Nine squares are chosen at random on a chessboard. What is the probability that they form a square of size $3\times 3$ ? (a) $\frac{9}{64}{C}_9$ (b) $\frac{36}{64}{C}_9$ (c) $\frac{6}{{}^4{\mathrm{C}}_9}$ (d) none of these

Seven digits from the numbers $1,2,3,4,5,6,7,8$ and 9 are written in random order. The probability that this seven digit number is divisible by 9 is : (a) $\frac{7}{9}$ (b) $\frac{1}{9}$ (c) $\frac{2}{9!}$ (d) $\frac{4}{9}$