**CHAPTER 3. COMBINATORICS**

Exercise 1 Page 88

Four people are to be arranged in a row to have their picture taken. In how many ways can this be done?

**Solution**

Position1 can be taken by all the four students

Position2 can be taken by rest of the three students

Position3 can be taken by rest of the two students

Position4 can be taken by rest of the one student

Thus the total combinations of arrangements possible are:- \[4*3*2*1 = 24\] Or, We can say the total number of combinations are 4!

`## [1] 24`