Have a safe break everyone. Now see if you can crack this question (see what I did there?)
Ritchie's birthday landed on a Thursday this year. He asks people at random if they have two children and also if one is a
boy born on a Thursday. After a long search he finally finds someone who
answers yes. What is the probability that this person's two children are both boys?
Assume an equal chance of giving birth to either sex and an equal chance
to giving birth on any day of the week.
There is a 50 percent chance of the other child to be a boy as he asked if the person had a child born on a thursday therefore the other child has a 50 percent chance. Also they already have a child born on a Thursday if they answered yes but for the other person, there is a 1 out of 7 chance (7 days a week).
ReplyDeleteADD ON:
Delete1/7*1/2=1/14 so there is a 1/14 or 7.14% for the other child to be a boy born on a Thursday
(He already asked if one child is a boy and if they said yes, the other child has a 50% chance of being a boy)
25% chance of being double boy see father has xx and mother is xy so there is a filthy person chance that it is one boy and a 25% and to be born on thursday is 1/7 so the possibility is 1/7 plus 1/4 is 11/28 and that is 39.2857%
ReplyDelete33% because the other options would be GG, BG, BB
ReplyDeleteso there is a 1/3 chance for each
Boy=B
ReplyDeleteGirl=G
Possibilities: GG, GB, BB
1/7 chance of the boy being born on a Thursday as there are seven days in a week
There is a 1/3 chance of both siblings being boys but since they answered that one of their children is a boy born on a Thursday the chance of having a male brother is 50% or 1/2 as the other child can be either a boy or girl. And also because they said that their child is born on a thursday it is now a 90% chance of the child being born on a Thursday as the parents may be lying
never mind BG and GB is the same thing = 33.3333333333333333333333333333333333333333% so it's 1/3 plus 1/7 10/21=47.619
ReplyDeleteNew answer: 20%
ReplyDelete2 children is the max (guess)
The options are
B
BB
G
GG
GB
100/5 = 20 so 20%
13/27, Mr. Milette told us
ReplyDeleteBut the "how" is important, not just the answer. That is a key component to math problems Neha. Can you explain how you would get this answer? I say you had a method in class.
DeleteThere is a 50% chance of the other child being a boy and a 14.28% chance of the child being born on a Thursday. Therefore, the chance of the child being both a boy and born on a Thursday would be 7.14%!
ReplyDelete