एक शतरंज की बिसात (chessboard) के तीन वर्ग यादृच्छिक रूप से चुने जाते हैं। एक ही रंग के 2 वर्ग और दूसरे भिन्न रंग के 1 वर्ग मिलने की प्रायिकता क्या है?

A box contains 'x + 4' red, 'x – 1' green and 'x – 5' blue balls. If two balls are drawn from the bag one after another without replacement, then the probability of getting one red and one green ball is equal to the probability of getting a sum equal to or more than 8 when two fair dice are rolled. Find the probability of drawing a red ball when one ball is drawn at random from the bag.

Four persons are chosen at random from a group containing 3 men, 2 women, and 4 children. The probability that exactly two of them are children is: