Suppose there are 21 students in your class. If the teacher draws 2 names at random, what is the probability that you and your best friend will be chosen?
2/21
1/20
1/105
2/10
Mine had different possible answers, mine was 1/210. I'm not sure how it got there but that's what it was. Sorry i prob didn't help much.
its 1/210
Its 1 1/210 I just answered it on switched on schoolhouse, Hope this helps!!! (:
1/210
A specific two names out of 21? What do you think?
To find the probability that you and your best friend will be chosen, we need to consider the total number of possible outcomes and the number of favorable outcomes.
The total number of possible outcomes is the number of ways the teacher can choose 2 students out of the 21 students in the class. This can be calculated using the combination formula, which is nCr = n! / (r! * (n-r)!), where n is the total number of items and r is the number of items being chosen at a time.
In this case, we have 21 students and we want to choose 2 of them, so the total number of possible outcomes is 21C2 = 21! / (2! * (21-2)!) = 21! / (2! * 19!) = (21 * 20) / (2 * 1) = 210.
Now, for the number of favorable outcomes, we want both you and your best friend to be chosen. Since there are only 2 of you, there is only 1 way to choose you, and once you have been chosen, there is only 1 way to choose your best friend from the remaining students. Therefore, the number of favorable outcomes is 1.
Thus, the probability of you and your best friend being chosen is 1/210, which can be simplified to 1/105.
Therefore, the correct answer is 1/105.
P.s.
Remember your best friend is one person!
1
_____
20
I ran into the exact same problem. PsyDAG was wrong because by taking out either you or your friend. That means there are less people, changing the possibility for the one left behind. The answer is 2/10 i think.
1/20 duh
2 students will be called out of 21 students.
this means that you will take 1 random student and subtract 1 from 21 because you can't get 2/20 then 3 people would have been chosen out of 21. Once you have the number 20 make a fraction with your best friend. 1/20 is what you guys should have got. If not you probably multiplied the denominators 20 and 21 and got 420 or if your dumb you got 210.