# Thread: Student Selection at random

1. ## Student Selection at random

18 juniors,,,,,,,10 seniors,,,,,(6 seniors are Female)(12 Juniors Male).....
Find the probability of a. A junior or a female?
b. A senior or a female?
c. A junior or a senior?

I suck at STATS.

2. i will do the first, try the other two, it's the same formula
Originally Posted by Hunt67
18 juniors,,,,,,,10 seniors,,,,,(6 seniors are Female)(12 Juniors Male).....
Find the probability of a. A junior or a female?
there are 28 students in all.

so we want $P(J \text{ or } F)$

using our formula, we have:

$P(J \text{ or } F) = P(J) + P(F) - P(J \text{ and } F) = \frac {18}{28} + \frac {6 + 6}{28} - \frac {6}{28} = \frac 67$

b. A senior or a female?
c. A junior or a senior?
have at them

I suck at STATS.
this is probability

3. Originally Posted by Jhevon
i will do the first, try the other two, it's the same formulathere are 28 students in all.

so we want $P(J \text{ or } F)$

using our formula, we have:

$P(J \text{ or } F) = P(J) + P(F) - P(J \text{ and } F) = \frac {18}{28} + \frac {6 + 6}{28} - \frac {6}{28} = \frac 67$

have at them

this is probability
I am confulsed with C. a junior and a senior. If i apply the formula i get 0/28????

4. Originally Posted by Hunt67
I am confulsed with C. a junior and a senior. If i apply the formula i get 0/28????
how is that? it is a junior or a senior, so that is P(J) + P(S) - P(J and S). here, of course, P(J and S) = 0 since you can't be a junior and senior at the same time, so you are left with P(J) + P(S)