A seven digit number is formed using digits $3 ,3,4,4,4,5,5 .$ The probability, that number so formed is divisible by $2,$ is ..... .
$\frac{6}{7}$
$\frac{1}{7}$
$\frac{3}{7}$
$\frac{4}{7}$
$3$ numbers are chosen from first $15$ natural numbers, then probability that the numbers are in arithmetic progression
A box contains $10$ red balls and $15$ green balls. If two balls are drawn in succession then the probability that one is red and other is green, is
If $12$ identical balls are to be placed in $3$ identical boxes, then the probability that one of the boxes contains exactly $3$ balls is :
Three mangoes and three apples are in a box. If two fruits are chosen at random, the probability that one is a mango and the other is an apple is
A man draws a card from a pack of $52$ playing cards, replaces it and shuffles the pack. He continues this processes until he gets a card of spade. The probability that he will fail the first two times is