Find the roots of the quadratic equation: 2x² + 3x - 9 = 0.

What smallest number should be added to 4456 so that the sum is completely divisible by 6?

Three 6-faced dice are thrown together. The probability that no two dice show the same number is -.

The sum of the digits of a two-digit number is 15 and the difference between the digits is 3. What is the two-digit number?

In a party, there are 5 couples. If 5 people are chosen at random, what is the probability that at least two of them are from the same couple?

A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is:

 Karna can do a piece of work in 6 hours; Dorbi and Sonal together can do it in 2 hours, while Karna and Sonal together can do it in 3 hours. How long will Dorbi alone take to do it? 

X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last? 

In a certain code language:

'put tir fin' means 'delicious juicy fruit';

'tie dip sig' means 'beautiful white lily'

and 'sig lon fin' means 'lily and fruit'.

Which of the following stands for 'and' in that language?

In chess, a knight moves two squares in one direction and one square in the other direction, ending up on the diagonally opposite corner of a 2x3 grid. Intervening squares can be occupied. Find the maximum number of knights that can be placed on an 8x8 chess board so that no knight threatens another knight (can move into a square occupied by one of the other knights).