Chapter 7 Permutations and Combinations
Q1. The value of P(n, n-1) is
a. n
b. n!
c. 2n
c. 2n!
Answer: (b) n!
Q2. The number of ways in which 8 students can be seated in a line is
a. 5040
b. 50400
c. 40230
d. 40320
Answer: (d) 40320
Q3. The number of ways 4 boys and 3 girls can be seated in a row so that they are alternate is
a. 12
b. 104
c. 144
d. 256
Answer: (c) 144
Q4. A coin is tossed n times, the number of all the possible outcomes is
a. 2n
b. 2n
c. C(n, 2)
d. P(n, 2)
Answer: (b) 2n
Q5. There are 10 true-false questions in an examination. These questions can be answered in:
a. 20 ways
b. 100 ways
c. 512 ways
d. 1024 ways
Answer: (d) 1024 ways
Q6. In how many ways can we paint the six faces of a cube with six different colours?
a. 30
b. 6
c. 6!
d. None of the above
Answer: (a) 30
Q7. There are 12 points in a plane out of which 5 are collinear. The number of triangles formed by the points as vertices is
(a) 185
(b) 210
(c) 220
(d) 175
Answer: (b) 210
Q8. Four dice are rolled. The number of possible outcomes in which at least one dice show 2 is
(a) 1296
(b) 671
(c) 625
(d) 585
Answer: (b) 671
Q9. If repetition of the digits is allowed, then the number of even natural numbers having three digits is
(a) 250
(b) 350
(c) 450
(d) 550
Answer: (c) 450
Q10. The number of ways can the letters of the word ASSASSINATION be arranged so that all the S are together is
(a) 152100
(b) 1512
(c) 15120
(d) 151200
Answer: (d) 151200