a store mixes red fescue worth $12 per pound and chewings fescue worth $16 per pound. The mixture is to sell for $15 per pound.
2 answers:
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Answer and working out attached below. Hope this helps
Answer:
95% Confidence interval for σ2 and for σ is (3.33 , 38.85) and (1.82 , 6.23) respectively.
Step-by-step explanation:
We are given that the amount of lateral expansion (mils) was determined for a sample of n = 7 pulsed-power gas metal arc welds used in LNG ship containment tanks. The resulting sample standard deviation was s = 2.83 mils.
Assuming data follows normal distribution.
So, firstly the pivotal quantity for 95% confidence interval for the population variance is given by;
P.Q. = ~
where, s = sample standard deviation = 2.83 mils
= population variance
= population standard deviation
n = sample size = 7
<em>So, 95% confidence interval for population variance, </em> <em>is;</em>
P(1.237 < < 14.45) = 0.95 {As the table of at 6 degree of freedom
gives critical values of 1.237 & 14.45}
P(1.237 < < 14.45) = 0.95
P( <
<
) = 0.95
P( <
<
) = 0.95
95% confidence interval for = (
,
)
= ( ,
)
= (3.33 , 38.85)
95% C.I. for population standard deviation, = (
,
)
= (1.82 , 6.23)
Therefore, 95% confidence interval for the population variance (σ2) and population standard deviation (σ) are (3.33 , 38.85) and (1.82 , 6.23) respectively.
Answer:
t ≈ -2.014 or 3.647
Step-by-step explanation:
Add the opposite of the expression on the right side of the equal sign to put the equation into standard form.
4.9t² -8t -36 = 0
You can divide by 4.9 to make this a little easier to solve.
t² -(8/4.9)t -36/4.9 = 0
Now, add and subtract the square of half the x-coefficient to "complete the square."
t² -(8/4.9)t +(4/4.9)² -36/4.9 -(4/4.9)² = 0
(t -4/4.9)² -192.4/4.9² = 0 . . . . simplify
Add the constant term, then take the square root.
(t -4/4.9)² = 192.4/4.9²
t -4/4.9 = ±(√192.4)/4.9
t = (4 ± √192.4)/4.9
t ≈ {-2.014, 3.647}
