What is the difference between the following two questions and how to solve both of them.

Q1) Two boys and four girlsare to be seated in a row in such a way that no two boys are together. How many seating arrangements are possible?

Q2) For a soccer match between German and Argentina, 7 Germans and 5 Argentines are standing at the ticket counter to buy the tickets. Every ticket bears a seat no. and the people with tickets bearing consecutive seat no.s sit together. The person issuing tickets at the counter is advised not to issue tickets bearing consecutive seat no.s to two Argentines. In how many ways can the tickets be issued?

(1) Four girls can be seated in a row in ways.

In each of these arrangements 5 places are created shown by the X mark

 

X G X G X G X G X

 

Since no two boys are to sit together, So we may arrange 2 boys in 5 places. 

This can be done in ways. i.e. 2 boys can be seated in ways.

 

Hence, the total number of seating arrangements

 

 

(2)

7 Germans can be seated in a row in ways. 

In each of these arrangements 8 places are created shown by X mark

 

X G X G X G X G X G X G X G X

 

Since no two Argentines are to sit together, so we may arrange 5  Argentines in 8 places. 

This can be done in ways i.e. 5 Argentines can be seated in ways.

 

Hence total number of ways

= 7! × 8 × 7 × 6 × 5 × 4 = 33868800

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