Step-by-step explanation:
There are 10 students and 11 faculty, for a total of 21 people.
7 individuals are chosen for the jury.
(a) There are ₁₀C₇ ways of choosing 7 individuals from 10 students.
There are ₂₁C₇ ways of choosing 7 individuals from 21 people.
So the probability that the individuals are all students is:
P = ₁₀C₇ / ₂₁C₇
P = 120 / 116280
P ≈ 0.00103
(b) There are ₁₁C₇ ways of choosing 7 individuals from 11 faculty.
There are ₂₁C₇ ways of choosing 7 individuals from 21 people.
So the probability that the individuals are all students is:
P = ₁₁C₇ / ₂₁C₇
P = 330 / 116280
P ≈ 0.00284
(c) There are ₁₀C₄ ways of choosing 4 individuals from 10 students.
There are ₁₁C₃ ways of choosing 3 individuals from 11 faculty.
There are ₂₁C₇ ways of choosing 7 individuals from 21 people.
So the probability that the individuals are all students is:
P = ₁₀C₄ ₁₁C₃ / ₂₁C₇
P = 210 × 165 / 116280
P ≈ 0.29799