Aptitude Discussion

Q. |
A teacher of $6$ students takes $2$ of his students at a time to a zoo as often as he can, without taking the same pair of children together more than once. How many times does the teacher go to the zoo? |

✖ A. |
10 |

✖ B. |
12 |

✔ C. |
15 |

✖ D. |
20 |

**Solution:**

Option(**C**) is correct

Two students can be selected from $6$ in ${^6C_2} = 15$ ways.

Therefore, the teacher goes to the zoo $15$ times.

**Pnr**

*()
*

**Ram**

*()
*

If there are 6 students and if he can take 2 at a time and not the same pair each time, then the number of times that he as to go to zoo is just 3!!!!

Am i missing something obvious here???

Ram, I guess you are missing the point that it is the not the "same pair"

let's say there are four students

$ABCD$

by your answer, it should be 4 times

BUT

ab

ac

ad

bc

bd

cd

are also pairs hence the teacher would ferry 6 times

Yes, your answer must have been correct only if it would have mentioned that no individual is repeated

I hope you got it :)

I guess it should be like ${^6C_2} \times {^4C_2} \times {^2C_2}$ $= 15 \times 6 \times 2$ $=180$ ways

Am I right?