Aptitude Discussion

Q. |
There are 10 stations on a railway line. The number of different journey tickets that are required by the authorities is: |

✖ A. |
92 |

✔ B. |
90 |

✖ C. |
91 |

✖ D. |
None of these |

**Solution:**

Option(**B**) is correct

From a certain station, there will be a ticket for each of the other 9 stations and there are 10 stations on the railway line.

The number of different journey tickets $=10×9=90$

**Pragya**

*()
*

**Parul**

*()
*

m not getting dis.. can u help me plz

Lets say there are 10 stations viz 1, 2, 3,4, 5, 6, 7, 8, 9, 10.

Now from station 1 you may go to station ~~1~~, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Thus total of 9 tickets are possible.

Similarly from station 2 you may go to station 1, ~~2~~, 3, 4, 5, 6, 7, 8, 9, 10. So total of 9 tickets are possible in this case too.

Similarly from every station you may go to every other station and 9 tickets are needed in every such case.

There are 10 such stations so total of $10*9$ tickets are possible/required by authorities.

solution by permutation: 10 P 2 = 90