Answer:
vertex = (2, - 9 )
Step-by-step explanation:
Given a quadratic in standard form : ax² + bx + c : a ≠ 0
Then the x- coordinate of the vertex is
= -
x² - 4x - 5 ← is in standard form
with a = 1, b = - 4, thus
= -
= 2
Substitute this value into the quadratic for corresponding value of y
(2)² - 4(2) - 5 = 4 - 8 - 5 = - 9
vertex = (2, - 9 )
Answer: 1.303639
Step-by-step explanation:
The t-score for a level of confidence is given by :_
, where df is the degree of freedom and
is the significance level.
Given : Level of significance :
Then , significance level :
Sample size :
Then , the degree of freedom for t-distribution:
Using the normal t-distribution table, we have
Thus, the t-score should be used to find the 80% confidence interval for the population mean =1.303639