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mart [117]
3 years ago
8

The mean length of long-distance telephone calls placed with a particular phone company was known to be 7.8 min under an old rat

e structure. In an attempt to be more competitive with other long-distance carriers, the phone company lowered long-distance rates, thinking that its customers would be encouraged to make longer calls and thus that there would not be a big loss in revenue. Let μ denote the true mean length of long-distance calls after the rate reduction. What hypotheses should the phone company test to determine whether the mean length of long-distance calls increased with the lower rates?
Mathematics
1 answer:
yarga [219]3 years ago
5 0

Answer:

H0: μ = 7.8

Ha: μ > 7.8

Step-by-step explanation:

The null hypothesis (H0) tries to show that no significant variation exists between variables or that a single variable is no different than its mean. While an alternative Hypothesis (Ha) attempt to prove that a new theory is true rather than the old one. That a variable is significantly different from the mean.

For the case above;

Let μ represent the true mean length of long-distance calls after the rate reduction

The null hypothesis is that true mean length of long-distance calls after the rate reduction is the same and equal to 7.8 minutes

H0: μ = 7.8

The alternative hypothesis is that the true mean length of long-distance calls after the rate reduction have increased that is greater than 7.8 minutes

Ha: μ > 7.8

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TEA [102]

Answer: False.

Step-by-step explanation:

For any random variable x,

Formula to calculate the z-score : z=\dfrac{x-\mu}{\sigma}

, where \mu = Mean

\sigma = Standard deviation

Let x be the data point has a corresponding z-score of -1.5.

Then , we have

-1.5=\dfrac{x-\mu}{\sigma}

-1.5\sigma=x-\mu

\mu-1.5\sigma=x

i.e. x is one and a half standard deviations below the mean value.

( one and a half =1+\dfrac{1}{2}=1.5 )

Therefore , the given statement is false.

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Answer:

Step-by-step explanation:

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2 years ago
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Marrrta [24]

Answer: The answer is (A) [0,100].


Step-by-step explanation:  Given in the question that a marine biologist Kelsey determined that the population of Blue Whales off the coast of Antarctica varies with time as shown in the given graph.

The population of Blue Whales (y) is plotted on the Y-axis and the time in months (x) is plotted on the X-axis.

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We can see from the attached graph that

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when x = 10, then y = 100.

That is, when time varies between 0 to 10 months, then the population of Blue Whales varies between 0 and 100.

Thus, the correct option is (A) [0,100].

7 0
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Vikentia [17]
Yes, you can take a photo of your question. You push the camera button at the bottom of the page.
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