A university found that 20% of its students withdraw without completing the introductory statistics course. Assume that 20 stude
1 answer:
Answer:
Step-by-step explanation:
Given that a university found that 20% of its students withdraw without completing the introductory statistics course.
Each student is independent of the other and there are only two outcomes
X no of students in the registered 20 is binomial with p = 0.2
a)the probability that two or fewer will withdraw.
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b. Compute the probability that exactly four will withdraw.
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c. Compute the probability that more than three will withdraw.
d. Compute the expected number of withdrawals.
E(x) = np = 4
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Answer:
(- 7, - 2 ) , (9.5, 0.75 )
Step-by-step explanation:
Given the equations
x - 6y = 5 ( add 6y to both sides )
x = 5 + 6y → (1)
xy - 2y² = 6 → (2)
Substitute x = 5 + 6y into (2)
(5 + 6y)y - 2y² = 6 ← distribute and rearrange left side
5y + 6y² - 2y² = 6
4y² + 5y = 6 ( subtract 6 from both sides )
4y² + 5y - 6 = 0 ← in standard form
(y + 2)(4y - 3) = 0 ← in factored form
Equate each factor to zero and solve for y
y + 2 = 0 ⇒ y = - 2
4y - 3 = 0 ⇒ 4y = 3 ⇒ y = = 0.75
Substitute these values into (1) for corresponding values of x
y = - 2 : x = 5 + 6(- 2) = 5 - 12 = - 7 ⇒ (- 7, - 2 )
y = 0.75 : x = 5 + 6(0.75) = 5 + 4.5 = 9.5 ⇒ (9.5, 0.75 )