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So I am struggling with a probability question can anyone help me. Super desperate!

Question: 10 different names are put into a computer one of the names is Colin. On Saturday, the computer chooses 2 names are random. The computer is set so that the same name can be chosen twice. What is the probability that Colin is chosen at least once?
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Broque_
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There are 10 names so the probability of getting Colin is 1/10.

As the name can be chosen twice, the possible combinations which satisfy the criteria are: (Colin, Not Colin) or (Colin, Colin) or (Not Colin, Colin).

Therefore we add these probabilities as it’s either one of them (rule of thumb: or=add+), so it will be (C=Colin, NC=Not Colin): p(C,NC)+p(C,C)+p(NC,C)=(1/10*9/10) + (1/10*1/10) + (9/10*1/10), then calculate and write down the answer.

Note: No mark schemes will require probabilities to be simplified
Original post by vb1022
So I am struggling with a probability question can anyone help me. Super desperate!

Question: 10 different names are put into a computer one of the names is Colin. On Saturday, the computer chooses 2 names are random. The computer is set so that the same name can be chosen twice. What is the probability that Colin is chosen at least once?

The simplest approach (IMO) is to calculate the probability of Colin not being chosen at all, then subtract that from 1 to get the probability of it being chosen at least once.

For bonus points, calculate the probability of Colin being chosen at least once in 10 draws.
(edited 3 years ago)
I hope this helps:smile:
Its just a picture of the working out that I was taught during GCSE's on how to work out probabilities
IMG_20200519_162555[1].jpg511.0KB
Original post by vb1022
So I am struggling with a probability question can anyone help me. Super desperate!

Question: 10 different names are put into a computer one of the names is Colin. On Saturday, the computer chooses 2 names are random. The computer is set so that the same name can be chosen twice. What is the probability that Colin is chosen at least once?


this would be my approach
7512F985-50F4-455F-B2B9-EBBD98CA84C9.jpg.jpeg

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