C. Find the length of the confidence interval

Spencer Marvin P. Esguerra

Spencer Marvin P. Esguerra

Answered question

2022-06-20

C. Find the length of the confidence interval given the following data:(s – sample

standard deviation)

1. 𝑠 = 2.36, n = 350, confidence level: 99%

2. 𝑠 = 3.35, n = 250, confidence level: 99%

3. 𝑠 = 3, n = 275, confidence level: 95%

4. 𝑠 = 6, n = 425, confidence level: 98%

5. 𝑠 = 9, n = 501, confidence level: 99%

Answer & Explanation

star233

star233

Skilled2022-09-14Added 403 answers

1. The given data are as follows,

Sample standard deviation (s) is 2.36

Sample size (n) is 350

Confidence level is 99%

Level of significance level (α)

= 100-99

= 1%

α = 0.01

p-value

= [1-(α/2)]

= [1-(0.01/2)]

= 0.995

From standard normal table,

Critical value z at 0.995 is 2.5762.58

Error margin

= {Zα/2*[s/sqr root(n)]}*2

= {2.58*[2.36/sqr root(350)]}*2

= 0.32546005*2

= 0.6509

Therefore confidence interval is 0.6509

 

 

2. The given data are as follows,

Sample standard deviation (s) is 3.35

Sample size (n) is 250

Confidence level is 99%

Level of significance level (α)

= 100-99

= 1%

α = 0.01

p-value

= [1-(α/2)]

= [1-(0.01/2)]

= 0.995

From standard normal table,

Critical value z at 0.995 is 2.5762.58

Error margin

= {Zα/2*[s/sqr root(n)]}*2

= {2.58*[3.35/sqr root(250)]}*2

= 0.546631316*2

= 1.0933

Therefore confidence interval is 1.0933

 

3. The given data are as follows,

Sample standard deviation (s) is 3

Sample size (n) is 275

Confidence level is 95%

Level of significance level (α)

= 100-95

= 5%

α = 0.05

p-value

= [1-(α/2)]

= [1-(0.05/2)]

= 0.975

From standard normal table,

Critical value z at 0.975 is 1.96

Error margin

= {Zα/2*[s/sqr root(n)]}*2

= {1.96*[3/sqr root(275)]}*2

= 0.354577341*2

= 0.7092

Therefore confidence interval is 0.7092

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