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1 answer:
Problem 1
Answer: C) No solution
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Explanation:
We have z = -4 and 4z = -4 at the same time. Solving 4z = -4 leads to z = -1
So in effect we have z = -4 and z = -1 at the same time, but this is a contradiction. A variable can only hold one number at a time.
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Problem 2
Answer: C) Infinitely many solutions
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Explanation:
The two equations are equivalent. You can prove as such by isolating 2y in the first equation.
5x = 8-2y
5x+2y = 8
2y = 8-5x
2y = -5x+8
-5x+8 = 2y
This shows the first equation is equivalent to the second, and vice versa. They both graph the same line. Any point along the line is a solution. So that's why there are infinitely many of them.
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Problem 3
Answer: Choice A)
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Explanation:
The range is the set of the possible y values. We're concerned with every y coordinate of each (x,y) solution. So we only focus on the shaded region.
The dashed line means we exclude the boundary. It's an electric fence we cannot touch. So y > -6 or -6 < y describes part of the range
The other part is since y = 3 is the when the highest point occurs.
So writing describes all possible y values of each (x,y) solution in the shaded region.
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Answer:
So the p value obtained was a very low value and using the significance level given we have
so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of subscribers that would upgrade to a new cellphone at a reduced cost is significantly higher than 0.2 or 20%
Step-by-step explanation:
Data given and notation
n=500 represent the random sample taken
X=135 represent the subscribers that would upgrade to a new cellphone at a reduced cost
estimated proportion of subscribers that would upgrade to a new cellphone at a reduced cost
is the value that we want to test
represent the significance level
Confidence=95% or 0.95
z would represent the statistic (variable of interest)
represent the p value (variable of interest)
Concepts and formulas to use
We need to conduct a hypothesis in order to test the claim that true proportion is higher than 0.2 or not.:
Null hypothesis:
Alternative hypothesis:
When we conduct a proportion test we need to use the z statistic, and the is given by:
(1)
The One-Sample Proportion Test is used to assess whether a population proportion is significantly different from a hypothesized value
.
Calculate the statistic
Since we have all the info required we can replace in formula (1) like this:
Statistical decision
It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.
The significance level provided . The next step would be calculate the p value for this test.
Since is a right tailed test the p value would be:
So the p value obtained was a very low value and using the significance level given we have
so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of subscribers that would upgrade to a new cellphone at a reduced cost is significantly higher than 0.2 or 20%