Probabilities

posted by .

Bibi wants to send invitations to some of her friends to come to her birthday party. She has contact information for 37 friends stored on her phone, but she only wants to invite 21 of those people to her party. She tries to send out a message to the 21 people, but her phone malfunctions and sends the message to three random contacts. The probability that exactly one person who got the invitation was not supposed to be invited to the party can be expressed as ab, where a and b are positive, coprime numbers. What is the value of a+b?

Similar Questions

1. math

You are having a pool party and invite 2 of your best friends. These two friends each invite two other people. Each of these 2 people invite 2 people that haven't been invited. How many people will be invited if this process continues …

3. English

Though you once told me this exercise was not very appropriate I’d like to know if there are alternatives to the ones I chose: Complete the verbs in the phrases p……… football play football g……… advice give advice b………… …
4. math

Penelope is having a party for her friends. She invited ten friends and seven have said they will come. Three of Penelope’s friends haven’t responded yet. Penelope needs to buy party supplies. Which sentence below is true of this …
5. Essay

Essay: How I surprised my friend on her birthday part. A birthday party is the one day a year, which is very special and unique to everyone in their life. It is a day that should be celebrated with lots of joys and some surprises. …
6. Math

Liam mailed 8 invitations to his birthday party. If one invitation went to each of his friends, how many friends did Liam invite to his party?
7. math

Bibi wants to send invitations to some of her friends to come to her birthday party. She has contact information for 37 friends stored on her phone, but she only wants to invite 21 of those people to her party. She tries to send out …
8. maths

Bibi wants to send invitations to some of her friends to come to her birthday party. She has contact information for 37 friends stored on her phone, but she only wants to invite 21 of those people to her party. She tries to send out …