probability question (1 Viewer)

[blackops23]

samantha has 3 similar keys in her pocket. to open her front door she tried the keys at random. she stopped trying when she opened the door and she did not use the same key twice
find the probability that
(1) the door opened when she tried the first key
2 she tried all three keys before the door opened


I got 1/3 for both questions. however it doesn't seem quite right can someone please help thank you

 

[asianese]

Draw a tree diagram - this will help.

 

[RealiseNothing]

At first glance you are right.

 

[Menomaths]

The answers seem to be 1/3

 

[blackops23]

another one:-@
(1) find the probability that in a family of four children 2 are boys and 2 are girls

i got 3/8

(2) 2 women each have four children. what is the probability that neither woman has two boys and two girls

25/64?

 

[obliviousninja]

monty hall problem, anyone?

 

[braintic]

Draw a tree diagram - this will help.

No need for a tree diagram here.

The probability that any one key is the correct one is 1/3 - whether its the 1st, 2nd or 3rd key tried.

 

[asianese]

To be fair the question doesn't stipulate how many of the keys work so it's ambiguous