# Permutation and Combination Quiz 12

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# Permutation and Combination Quiz 12

### Introduction

Permutation and Combination is one of important topic in Quantitative Aptitude Section. In Permutation and Combination Quiz 12 article candidates can find questions with answer. By solving this questions candidates can improve and maintain, speed, and accuracy in the exams. Permutation and Combination Quiz 12 questions are very useful for different exams such as IBPS PO, Clerk, SSC CGL, SBI PO, NIACL Assistant, NICL AO, IBPS SO, RRB, Railways, Civil Services etc.

### Q1

In how many ways can 7 beads be strung into necklace ?
A. 2520 B. 5040 C. 720 D. 360

D
No of way in Necklace = $\frac {(n-1)!}{2} = \frac {6!}{2}$
= $\frac {720}{2} = 360$

### Q2

Find the no of 3 digit numbers such that at least one of the digit is 6 (with repetitions) ?
A. 252 B. 345 C. 648 D. 560

A
Total no of 3 digit number = $9 \times 10 \times 10 = 900$
No of 3 digit number- none of the digit is $6 = 8 \times 9 \times 9 = 648$ v
No of 3 digit number – at least one digit is 6 = 900 - 648 = 252

### Q3

In how many ways can 7 girls and 4 boys stand in a row so that no 2 boys are together ?
A. 8467200 B. 9062700 C. 7407000 D. 8407200

A
No of ways = $7! \times {8}^{P}_{4}$
7! = 5040
${8}^{P}_{4} = 8 \times 7 \times 6 \times 5 = 1680$
No of ways = $5040 \times 1680 = 8467200$

### Q4

How many numbers can be formed with the digits 1, 7, 2, 5 without repetition ?
A. 89 B. 56 C. 64 D. 72

C
1 digit number = 4
2 digit no = $4 \times 3 = 12$
3 digit no = $4 \times 3 \times 2 = 24$
4 digit no = $4 \times 3 \times 2 \times 1 = 24$
Total = 4 + 12 + 24 + 24 = 64

### Q5

There are 3 boxes and 6 balls. In how many ways these balls can be distributed if all the balls and all the boxes are different?
A. 243 B. 512 C. 729 D. 416

C
${3}^{6} = 729$