The rational number which equals the number `bar(2. 357) ` with recurring decimal is a.`(2355)/(1001)` b. `(2379)/(997)` c. `(2355)/(999)` d. none of these

The total number of ways in which 2n persons can be divided into n couples is a. (2n !)/(n ! n !) b. (2n !)/((2!)^3) c. (2n !)/(n !(2!)^n) d. none of these

There are four letters and four directed envelopes. The number of ways in which all the letters can be put in the wrong envelope is a. 8 b. 9 c. 16 d. none of these

In the decimal system of numeration of six-digit numbers in which the sum of the digits is divisible by 5 is a. 180000 b. 540000 c. 5xx10^5 d. none of these

The number of ways in which we can select four numbers from 1 to 30 so as to exclude every selection of four consecutive numbers is a. 27378 b. 27405 c. 27399 d. none of these

If a,b,c and d are four unequal positive numbers which are in A.P then

Total number of six-digit number in which all and only odd digits appear is a. 5/2(6!) b. 6! c. 1/2(6!) d. none of these

Let f(x)=2x+1. Then the number of real number of real values of x for which the three unequal numbers f(x),f(2x),f(4x) are in G.P. is 1 b. 2 c. 0 d. none of these

Two congruent circles with centered at (2, 3) and (5, 6) which intersect at right angles, have radius equal to (a)2 sqrt(3) (b) 3 (c) 4 (d) (d) none of these

The total number of ways in which n^2 number of identical balls can be put in n numbered boxes (1,2,3,.......... n) such that ith box contains at least i number of balls is a. .^(n^2)C_(n-1) b. .^(n^2-1)C_(n-1) c. .^((n^2+n-2)/2)C_(n-1) d. none of these

A die is rolled 4 times. The probability of getting a larger number than the previous number each time is a. 17//216 b. 5//432 c. 15//432 d. none of these