Probabilty with random variable

[DotKite]

Homework Statement

A couple is expecting the arrival of a new boy. They are deciding on a name
from the list S = { Steve, Stanley, Joseph, Elija }. Let X(ω) = first letter in
name. Find Pr(X = S).

Homework Equations

The Attempt at a Solution

Ok the answer is 2/3. How is it 2/3? Shouldnt it be 1/2?

 

[Ray Vickson]

Homework Statement

A couple is expecting the arrival of a new boy. They are deciding on a name
from the list S = { Steve, Stanley, Joseph, Elija }. Let X(ω) = first letter in
name. Find Pr(X = S).

Homework Equations

The Attempt at a Solution

Ok the answer is 2/3. How is it 2/3? Shouldnt it be 1/2?

I would say it is 1/2, assuming that each of the names in S is equally likely.

 

[haruspex]

Ok the answer is 2/3. How is it 2/3? Shouldnt it be 1/2?

Strange.. are you sure you have quoted the whole question word-for-word?

 

[h6ss]

I remember having seen this exact same question in a preparation exam for P/1.

I remember it because the solution said 2/3 and it was obviously wrong. :p

 

[HallsofIvy]

IF that is the full statement of the problem, it is incomplete. It must say, at the least, that the four names on the list are "equally likely".

 

[Mentallic]

Could Elija be a girl's name and maybe this has something to do with it? Out of the set of 4 names, if Elija is never going to be chosen since they're expecting a boy, then we actually have 2/3 of the possible names starting with S.

 

[LCKurtz]

Could Elija be a girl's name and maybe this has something to do with it? Out of the set of 4 names, if Elija is never going to be chosen since they're expecting a boy, then we actually have 2/3 of the possible names starting with S.

I agree. That answer certainly suggests a conditional probability question which likely has been incompletely stated.

 

[NascentOxygen]

Could Elija be a girl's name and maybe this has something to do with it? Out of the set of 4 names, if Elija is never going to be chosen since they're expecting a boy, then we actually have 2/3 of the possible names starting with S.

Some sites list it as a boy's name, others as a girl's. This site says it's about as likely to be for one as for the other. http://www.gpeters.com/names/baby-names.php?name=Elija

So that doesn't help much, does it?

 

[Mentallic]

Some sites list it as a boy's name, others as a girl's. This site says it's about as likely to be for one as for the other. http://www.gpeters.com/names/baby-names.php?name=Elija

So that doesn't help much, does it?

Let's assume that this particular couple considers it to be a girl's name

It's a fair assumption to make seeing as how poorly constructed the question is.