Recent questions tagged difficult

If for a distribution $ \sum (x-5) =3,\sum (x-5)^2 =43$ and the total number of items is $18$. Find the mean and standard deviation .

asked Jul 4, 2014 by meena.p

1 answer

Two sets each of $20$ observations , have the same standard deviation $5$. The first set has a mean $17$ and the second a mean $22$. Determine the standard deviation of the set obtained by combining the given two sets.

asked Jul 3, 2014 by meena.p

1 answer

If four digit numbers greater than 5000 are randomly formed from the digits 0,1,3,5 and 7,what is the probability of forming number divisible by 5 when repetition of digits is not allowed.

asked Jul 3, 2014 by sreemathi.v

1 answer

If four digit numbers greater than 5000 are randomly formed from the digits 0,1,3,5 and 7,what is the probability of forming number divisible by 5 when the digits are repeated ?

asked Jul 3, 2014 by sreemathi.v

1 answer

From the employees of a company ,5 persons are selected to represent them in managing committee of the company.Particulars of five persons are as follows :

asked Jul 3, 2014 by sreemathi.v

1 answer

Find the equations of the lines through the point of intersection of the lines $x-y+1=0 $ and $ 2x-3y+5 = 0$ and whose distance from the point (3, 2) is $ \large\frac{7}{5}$

asked Jul 2, 2014 by thanvigandhi_1

1 answer

Three letters are dictated to three persons and an envelope is addressed to each of them,the letters are inserted into the envelopes at random so that each envelope contains exactly one letter.Find the probability that at least one letter is in its proper envelope.

asked Jul 2, 2014 by sreemathi.v

1 answer

The mean and standard deviation of a group of 100 observations were found to be 20 and 3, respectively . Later on it was found that three observations were incorrect. Which are recorded by 21,21, and 18 . Find the mean and standard deviation, if the incorrect observations are omitted.

asked Jul 2, 2014 by meena.p

1 answer

Out of 100 students,two sections of 40 and 60 are formed.If you and your friend are among the 100 students,what is the probability that,you both enter the different sections?

asked Jul 2, 2014 by sreemathi.v

1 answer

Out of 100 students,two sections of 40 and 60 are formed.If you and your friend are among the 100 students,what is the probability that,you both enter the same section

asked Jul 2, 2014 by sreemathi.v

1 answer

Given $\bar{x} $ is the mean and $\sigma^2$ is the variance of n observations $x_1,x_2,x_3......x_n$ prove that the mean and variance of the observations $ax_1,ax_2,ax_3.......ax_n$ are $a \bar{x}$ and $a^2\sigma^2$, respectively , $(a\neq 0)$

asked Jul 2, 2014 by meena.p

1 answer

The probability that a student will pass the final examination in both English and Hindi 0.5 and the probability of passing neither is 0.1.If the probability of passing the english examination is 0.75.What is the probability of passing the hindi examination?

asked Jul 2, 2014 by sreemathi.v

1 answer

Find the equation of the line which passes through the point (– 4, 3) and the portion of the line intercepted between the axes is divided internally in the ratio 5 : 3 by this point

asked Jul 1, 2014 by thanvigandhi_1

1 answer

A straight line moves so that the sum of the reciprocals of its intercepts made on axes is constant. Show that the line passes through a fixed point. \[\] [ Hint : $\large\frac{x}{a}$$ + \large\frac{y}{b}$$=1$ where $ \large\frac{1}{a}$$+\large\frac{1}{b}$ = constant = $ \large\frac{1}{k}$ (say ). This implies that $ \large\frac{k}{a}$$+\large\frac{k}{b}$$=1 \Rightarrow $ line passes through the fixed point (k, k).]

asked Jul 1, 2014 by thanvigandhi_1

1 answer

A variable line passes through a fixed point P. The algebraic sum of the perpendiculars drawn from the points (2, 0), (0, 2) and (1, 1) on the line is zero. Find the coordinates of the point P \[\] [Hint: Let the slope of the line be $m$. Then the equation of the line passing through the fixed point $P (x_1 , y_1 )$ is $y - y_1 = m (x - x_1 )$. Taking the algebraic sum of perpendicular distances equal to zero, we get $ y - 1 = m (x - 1). $ Thus $(x_1 , y_1 ) $ is $(1, 1)$.]

asked Jul 1, 2014 by thanvigandhi_1

1 answer

Find the equation of one of the sides of an isosceles right angled triangle whose hypotenuse is given by 3x + 4y = 4 and the opposite vertex of the hypotenuse is (2, 2).

asked Jul 1, 2014 by thanvigandhi_1

1 answer

If the intercept of a line between the coordinate axes is divided by the point (–5 4) in the ratio 1 : 2, then find the equation of the line.

asked Jul 1, 2014 by thanvigandhi_1

1 answer

For what values of a and b the intercepts cut off on the coordinate axes by the line ax + by + 8 = 0 are equal in length but opposite in signs to those cut off by the line 2x – 3y + 6 = 0 on the axes.

asked Jul 1, 2014 by thanvigandhi_1

1 answer

The sum and sum of squares corresponding to length x (in cm) and weight (y) in gm of 50 plant products are given below: $ \sum \limits _{i=1} ^{50} x_i=212, \qquad\sum \limits_{i=1}^{50}x_i^2 =902.8;\qquad \sum \limits _{i=1} ^{50} y_i=261, \qquad\sum \limits_{i=1}^{50}y_i^2 =1457.6$ Which is more varying , the length or weight?

asked Jul 1, 2014 by meena.p

1 answer

The following is the record of goals scored by team A in a football session. For Team B , mean number of goals scored per match was 2 with a standard deviation 1.25 goals. Find which team may be considered more consistent ?

asked Jul 1, 2014 by meena.p

1 answer

A fair coin is tossed four times and a person win Rs.1 for each head and lose Rs.1.50 for each tail that turns up.From the sample space,calculate how many different amounts of money you can have after four tosses and the probability of having each of these amounts.

asked Jul 1, 2014 by sreemathi.v

1 answer

From the prices of shares A and Y below. Find out which is more stable in value.

asked Jun 30, 2014 by meena.p

1 answer

From the data given below state which group is more variable A or B?

asked Jun 30, 2014 by meena.p

1 answer

An experiment consists of rolling a die and then tossing a coin once if the number on the die is even.If the number on the die is odd,the coin is tossed twice.Write the sample space for the experiment

asked Jun 26, 2014 by sreemathi.v

1 answer

Calculate the mean deviation about median for the age distribution of 100 persons given below.

asked Jun 26, 2014 by meena.p

1 answer

A coin is tossed .If the outcome is a head,a die is thrown.If the die shows up an even number,the die is thrown again.What is the sample space for the experiment.

asked Jun 26, 2014 by sreemathi.v

1 answer

Find the mean deviation about the median for the following data :

asked Jun 26, 2014 by meena.p

1 answer

If the coefficient of $x^7$ in the expansion of $(a^2x+b^{-1}x^{-1})^{11}$ is equal to the coefficient of $x^{-7}$ in $(ax-b^{-1}x^{-2})^{11}$ then $ab=$

asked Jun 25, 2014 by sreemathi.v

1 answer