Answer: The margin of error = 3.71, confidence interval = (354.04, 361.46) and it means that mean cost is lies within the confidence interval.

Step-by-step explanation:

Since we have given that

Sample size = 400

Mean = $357.75

Standard deviation = $37.89

At 95% confidence level, z = 1.96

We first find the margin of error.

Margin of error is given by

$z\times \dfrac{\sigma}{\sqrt{n}}\\\\=1.96\times \dfrac{37.89}{\sqrt{400}}\\\\=3.71$

95% confidence interval would be

$\bar{x}\pm \text{margin of error}\\\\=357.75\pm 3.71\\\\=(357.75-3.71,357.75+3.71)\\\\=(354.04,361.46)$

Hence, the margin of error = 3.71, confidence interval = (354.04, 361.46) and it means that mean cost is lies within the confidence interval.

7 0

4 years ago

Solve - 2/5x is less than or equal to 20

sashaice [31]

Answer:

x is less than or equal to 0

Step-by-step explanation:

- you need to multiply both sides of the inequality by 5/2

- then you reduce the numbers with the greatest common factor 5

- then you reduce the numbers with the greatest common factor 2

- any expression multiplied by 0 equals 0

- so you get x is less than or equal to 0

^^^ hope this helps! :)

8 0

3 years ago

A gumball machine has 200 red gum balls. if the red gumballs are 50% of the total number of gum balls, how many gumballs are in

lbvjy [14]

400 are in it 200x2 = 400

4 0

3 years ago

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