Find the total number of 8 digits numbers that can be formed, all having different digits.
9 × 9!
9 × 8!
(9/2) × 8!
Correct Answer is: (9/2)× 9!
In a question paper, there are four multiple-choice questions. Each question has five choices with only one choice for its correct answer. What is the total number of ways in which a candidate will not get all the four answers correct?
Correct Answer is: 624
A mixed doubles tennis game is to be played between two teams (each team consists of one male and one female). There are 4 married couples. No team is to consist of a husband and his wife. What is the maximum number of games that can be played?
Correct Answer is: 12
Let two husbands A & B, out of 4 husbands can be selected in 4C2 = 6 ways
Leaving wife of A & B, remaining 2 wives(C&D) can be selected in 2C2 = 1 way
Each of 2 women and 3 men is to occupy one chair out of 8 chairs, each of which is numbered from 1 to 8. First, women are to occupy any two chairs from those numbered 1 to 4; and then the 3 men would occupy any three chairs out of the remaining 6 chairs. What is the maximum number of different ways in which this can be done?
Correct Answer is: 1440
Since 2 females can sit on the chairs numbered 1 to 4 in 4P2 = 12 ways.
And on remaining 6 chairs, 3 males can sit in 6P3=120 ways
Total no of required arrangements: 12X120=1440
How many numbers are there in all from 6000 to 6999 (Both 6000 and 6999 included) having at least one of their digits repeated?
Correct Answer is: 496
All the six letters of the name SACHIN are arranged to form different words without repeating any letter in anyone word. The words so formed are then arranged as in a dictionary.
What will be the position of the word SACHIN in that sequence?
Correct Answer is: 601
Nine different letters are to be dropped in three different letter boxes. In how many different ways can this be done?
Correct Answer is: 3^9
In a question of a test paper, there are five items each under List-A and List-B. The examinees are required to match each item under List-A with its corresponding correct item under List-B. Further, it is given that
(i)No examinee has given the correct answer
(ii)Answers of no two examinees are identical
What is the maximum number of examinees who took this test?
Correct Answer is: 24
Three dice (each having six faces with each face having one number from 1 to 6) are rolled. What is the number of possible outcomes such that at least one dice shows the number 2?
Correct Answer is: 91
The No of total such results in which digit 2 is shown at least one dice = (total results) - (results which don't show the digit 2 )
= 6^3-5^3 = 216-125=91
Groups each containing 3 boys are to be formed out of 5 boys — A, B, C, D and E such that no one group contains both C and D together. What is the maximum number of such different groups?