Quiz Discussion

If ¹⁸C_r = ¹⁸C_r+2 ; find ^rC₅.

• 1]

  56

• 2]

  63

• 3]

  49

• 4]

  42

There are 20 people among whom two are sisters. Find the number of ways in which we can arrange them around a circle so that there is exactly one person between the two sisters.

• 1]

  2! x 19!

• 2]

  18!

• 3]

  18! x 2!

• 4]

  19!

Three chairs are arranged in a row facing three other chairs. 4 boys and 2 girls are to be seated on these chairs such that girls are always facing each other. In how many ways can they be seated?

• 1]

  96

• 2]

  72

• 3]

  144

• 4]

  120

A coin is tossed 5 times. What is the probability that head appears an odd number of times?

• 1]

  1/2

• 2]

  2/3

• 3]

  1/3

• 4]

  1

What is the sum of all 4 digit numbers that can be formed by the digits 1, 2, 3, 4 each exactly once

• 1]

  55566

• 2]

  66660

• 3]

  56456

• 4]

  84738

If P(A)=2/5​, P(B)=3/10​ and P(A ∩ B) =51​, then P(A' | B'). P(B' | A') is equal to

• 1]

  5/6

• 2]

  5/7

• 3]

  25/42

• 4]

  1

In how many ways can a cricketer can score 200 runs with fours and sixes only?

• 1]

  13

• 2]

  19

• 3]

  16

• 4]

  17

A fair coin is tossed 5 times. What is the probability of getting at least three heads on consecutive tosses?

• 1]

  3/16

• 2]

  1/4

• 3]

  7/24

• 4]

  5/16

The students in a class are seated, according to their marks in the previous examination. Once, it so happens that four of the students got equal marks and therefore the same rank. To decide their seating arrangement, the teacher wants to write down all possible arrangements one in each of separate bits of paper in order to choose one of these by lots. How many bits of paper are required?

• 1]

  24

• 2]

  12

• 3]

  36

• 4]

  48

How many natural numbers can be made with digits 0, 7, 8 which are greater than 0 and less than a million?

• 1]

  496

• 2]

  728

• 3]

  486

• 4]

  1084