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Answer with explanation:</u></h2>
The confidence interval for population mean (when population standard deviation is unknown) is given by :-
, where n= sample size
= Sample mean
s= sample size
t* = Critical value.
Given : n= 25
Degree of freedom : 
Significance level for 98% confidence interval : 
Using t-distribution table ,
Two-tailed critical value for 98% confidence interval :
⇒ The critical value that should be used in constructing the confidence interval = 2.4922
Then, the 95% confidence interval would be :-
Hence, the 98% confidence interval for the mean repair cost for the dryers. = 
Let n be the amount of 80% solution; and 150-n be the amount of 20% solution. Then:
.8n+.2(150-n)=.6(150)
.8n+30-.2n=90
.6n=60
n=100
150-n=50
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Answer:
x = -5/7, 2
Step-by-step explanation:
Step 1: Factor
(5x + 7)(x - 2) = 0
Step 2: Find <em>x </em>roots
5x + 7 = 0
x = -5/7
x - 2 = 0
x = 2
6.
4x^2 + 4 = 0
Divide both sides by 4
x^2 + 1 = 0
Use the quadratic formula since this cannot be factored.
x = (-b +- sqrt(b^2 - 4ac))/(2a)
x = +- sqrt(-4(1)(1))/2
x = +- sqrt(-4)/2
x = +- 2i/2
x = +- i
x = i or x = -i
Quicker solution:
If you have x^2 = number, then
x = +- sqrt(number)
Once you get to
x^2 + 1 = 0
Subtract 1 from both sides
x^2 = -1
Apply the quick method
x = +- sqrt(-1)
x = +- i
8.
2x^2 + 50 = 0
Divide both sides by 2
x^2 + 25 = 0
Subtract 25 from both sides
x^2 = -25
Apply quick method
x = +- sqrt(25)
x = +- 5i
x = 5i or x = -5i
C. A record of everything you earn.
