Mathematics Tes...

A box contains 3 white and 2 black balls. Two balls are drawn at random one after the other. If the balls are not replaced, what is the probability that both the balls are black?

For two variables x and y, the two regression coefficients are b_yx=$-\frac{3}{2}$ and b_xy= -$\frac{1}{6}$.The correlation coefficient between x and y is :

The variance of number$x^1,x^2,x^3,\dots \dots .x^n$,is V. Consider the following statement:

1.If every $x_1$ is increased by 2, the variance of the new set of numbers is V.

2. If the numbers $x_i$ is squared, the variance of the set is $V^2$.

Which of the following statement is/are correct ?

What is the mean of the squares of the first 20 natural numbers?

p, q, r, s, t, are five numbers such that the average of p, q and r is 5 and that of s and t is 10. What is the average of all the five numbers ?

The cumulative frequency of the largest observed value must always be:

It has been found that if A and B play a game 12 times, A wins 6 times, B wins 4 times and they draw twice. A and B take part in a series of 3 games. The probability that they win alternately, is:

Out of 7 consonants and 4 vowels, words are to be formed by involving 3 consonants and 2 vowels. The number of such words formed is:

Let X denote the number of scores which exceed 4 in 18, tosses of a symmetrical die. Consider the following statements:

1. The arithmetic mean of X is 6.

2. The standard deviation of X is 2.

Which of the above statements is/are correct?

How many different words can be formed by taking four letters out of the letters of the word ‘AGAIN’ if each word has to start with A?