Three coins are tossed simultaneously once, find the probability of getting atleast one tail is

A box contains 90 discs numbered from 1 to 90. If one disc is drawn at random from the box, the probability that it bears a prime number less than 23 is

If a two digit number is choosen at random, what is the probability that the number choosen is a multiple of 3?

A social studies text book contains 250 pages. A page is selected at random. What is the probability that the number on the page selected is a perfect square?

In a lucky dip of 30 tokens Ravi purchased two tokens. Then the probability of getting the first prize is

In a simultaneous toss of two coins, the probability of atleast one head is

When a dice is rolled the probability of getting a composite number is

The event of getting a number less than or equal to 6 in a dice rolling, is a ........

Three different greeting cards and their corresponding covers are randomly strewn about on a table. If Ravi puts the greeting cards into the covers at random, the probability of correctly matching of all greeting cards and covers is

In a box there are 28 marbles of which x are green and the rest are white. If the probability of getting a green marble is $\frac{2}{7}\backslash frac\{2\}\{7\}$ then the number of white marbles is