5, 8, 6 and k occur with frequency 3, 2, 4, and 1 respectively and have a mean of 5.7. Find the value of k?

What is the mean deviation of x, 2x, x+1 and 3x. If their mean is 2?

In how many ways can a delegation of 3 be chosen from 5 men and 3 women. If at least 1 man and 1 woman must be included?

In how many ways can 9 people be seated if 3 chairs are available?

The table above shows the distribution of marks of students in a test. Find the probability of passing the test if the pass mark is 5?