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Tcecarenko [31]
3 years ago
13

In an examination of purchasing patterns of shoppers, a sample of 36 shoppers revealed that they spent, on average, $50 per hour

of shopping. Based on previous years, the population standard deviation is $4.80 per hour of shopping. Assuming that the amount spent per hour of shopping is normally distributed, calculate a 90% confidence interval.
Mathematics
1 answer:
frutty [35]3 years ago
5 0

Answer:

the 90% confidence interval is ( 48.684  , 51.316  )

Step-by-step explanation:

Given that :

the sample size = 36

Sample Mean = 50

standard deviation = 4.80

The objective is to calculate a 90% confidence interval.

At 90% confidence interval ;

the level of significance = 1 - 0.9 = 0.1

The critical value for z_{\alpha/2} = z_{0.1/2}

= z_{0.05} = 1.645

The standard error S.E = \dfrac{\sigma}{\sqrt{n}}

=\dfrac{4.8}{\sqrt{36}}

=\dfrac{4.8}{6}

= 0.8

The Confidence interval level can be computed as:

\bar x  \ \pm z \times \ \dfrac{ \sigma }{\sqrt{n}}

For the lower limit :

\bar x  \ - z \times \ \dfrac{ \sigma }{\sqrt{n}}

=50 \ - 1.645  \times \ \dfrac{ 4.8 }{\sqrt{36}}

=50 \ - 1.645  \times \ 0.8 }}

=50 - 1.316

= 48.684

For the upper limit :

\bar x  \ - z \times \ \dfrac{ \sigma }{\sqrt{n}}

=50 \ + 1.645  \times \ \dfrac{ 4.8 }{\sqrt{36}}

=50 \ + 1.645  \times \ 0.8 }}

=50 + 1.316

= 51.316

Thus, the 90% confidence interval is ( 48.684  , 51.316  )

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The cost of a whole box of chips are $60. I have $48. What percentage of the total cost do I have?
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Answer:

Percentage of total I have = 80%    

Step-by-step explanation:

Given:

Price of Box = $60

I Have = $48

To Find:

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Solution:

In this question we are just supposed to find out the percentage of the Value we have so

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Now we have the values of all

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So the Percentage of total cost I have is 80%

Percentage of total = 80%    


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