Teesha is in the French club. There are 31 students in the club. The French teacher will pick two
students at random to guide visiting students from France. What is the probability that Teesha will be
picked as a guide? Hint: Teesha must be picked first or second.
a. 1/30
b. 30/31
c. 1/930
d. 2/31

In my mind I am thinking the first time a name is drawn, there is a 1/31 chance her name will be drawn. the second time there is only a 1/30 chance her name will be picked. I multiplied those and got 1/930

Then again, I am also thinking there are 2/31 chances her name could be drawn.

Question

Teesha is in the French club. There are 31 students in the club. The French teacher will pick two
students at random to guide visiting students from France. What is the probability that Teesha will be
picked as a guide? Hint: Teesha must be picked first or second.
a. 1/30
 b. 30/31 
c. 1/930 
d. 2/31

In my mind I am thinking the first time a name is drawn, there is a 1/31 chance her name will be drawn. the second time there is only a 1/30 chance her name will be picked. I multiplied those and got 1/930 

Then again, I am also thinking there are 2/31 chances her name could be drawn.

welshfella · Answer

what is the probabilty that Teesha will be picked first?

bookworm14 · Answer

1/31

welshfella · Answer

she is 1 of 31 students 
yes

welshfella · Answer

now the other favourable scenario is that she is picked second
the probability that she is not picked first time is 30/31
what is the proability she is picked on the second  choice?

welshfella · Answer

- after not being picked  on first choice

bookworm14 · Answer

wouldn't it be 1/30 ? because there will only be 30 options left if someone else got picked the first time

welshfella · Answer

yes

perfect14 · Answer

no it would be 2/30 because she has two chances to be picked

welshfella · Answer

So probabilty first choice  =  1/31
probability  chosen second = 30/31 * 1/30
Required probabilty is the sum of these 2.

welshfella · Answer

No 1/30 was right

welshfella · Answer

a tree diagram is a good way of doing this one

bookworm14 · Answer

ok, my answers i was torn between when i initially posted this question were C and D, and I posted my thought process on how I came to either of those conclusions. were either of those right?

welshfella · Answer

P(picked first) = 1/31
P( not picked then picked = 30/31 8 1/30 = 1/31

required probability = 1/31 + 1/31

welshfella · Answer

* that 8 should be a *

welshfella · Answer

the 2 scenarios cannot both occur so the  probabilities are added

bookworm14 · Answer

ok, that made way more sense, somehow i kept getting 29 based on ur first description ( i was typin it in wrong) so D is the answer?

welshfella · Answer

yes

welshfella · Answer

when its P1 OR P2   ADD P's
when its P1 AND P2  multiply the P's

bookworm14 · Answer

ok thank you!