There are some coins and rings of either gold or silver in a box. 60% of the objects are coins, 40% of the rings are of gold and 30% of the coins are silver. What is the percentage of gold articles?

In how many different ways can the letters of the word 'NATIONAL' be arranged?

In a bag there are 4 white, 4 red and 2 green boxes. Two boxes are drawn at random. What is the probability that at least one boxes is of red colour?

From a pack of 52 cards, two cards are drawn together at random. What is the probability of both the cards being kings?

A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?