Each of the 11 letters A, H, I, M, O, T, U, V, W, X and Z appears same when looked at in a mirror. They are called symmetric letters. Other letters in the alphabet are asymmetric letters.
How many three-letter computer passwords can be formed (no repetition allowed) with at least one symmetric letter?
990
2730
12780
1560000
A box contains 6 red balls, 7 green balls and 5 blue balls. Each is of different size.the probability that the red ball selected is the smallest red ball is
1/18
1/3
1/6
2/3
Boxes numbered 1, 2, 3, 4 and 5 are kept in a row, and they which are to be filled with either a red or a blue ball, such that no two adjacent boxes can be filled with blue balls. Then, how many different arrangements are possible, given that all balls of a given colour are exactly identical in all respects?
8
10
15
22
A, B, C and D are four towns, any three of which are non-collinear. Then, number of ways to construct three roads each joining a pair of towns so that roads do not form a triangle is
7
8
9
24
If a 4 digit number is formed with digits 1, 2, 3 and 5. What is the probability that the number is divisible by 25, if repetition of digits is not allowed?
1/12
1/4
1/6
None of these
A man has 9 friends 4 boys and 5 girls. In how many ways can he invite them, if there have to be exactly 3 girls in the invitees?
320
160
80
200
In how many ways can eight directors, Vice-chairman and Chairman of a firm be seated at a round table if the Chairman has to sit between the Vice-chairman and a director?
9! * 2
2 * 8!
2 * 7!
None of these
How many numbers can be formed from 1, 2, 3, 4, 5 (without repetition), when the digit at unit’s place must be greater than that in ten’s place?
54
60
51/3
2 * 4!
An intelligence agency forms a code of two distinct digits selected from 0, 1, 2,……,9 such that the first digit of the code is nonzero. The code, handwritten on slip, can however potentially create confusion, when read upside down-for example, the code 91 may appear as 16. How many codes are there for which no such confusion can arise?
80
78
71
69
15
56
120
336
A new flag is to be designed with six vertical stripes using some or all of the colours yellow, green, blue and red. Then, the number of ways this can be done such that no two adjacent stripes have the same colour is:
12*81
16*192
20*125
24*216
In a chess competition involving some boys n girls of a school, every student had to play exactly one game with every other student. It was found that in 45 games both the players were girls and in 190 games both were boys. The number of games in which one player was a boy and the other was a girl is
200
216
235
256
/
R>1.0
2
0
If ??=(163+173+183+193), then ?? divided by 70 leaves a remainder of
0
1
69
35