Solved on Dec 05, 2023

Find the margin of error for c=0.95c=0.95, s=4s=4, and n=8n=8.

STEP 1

Assumptions
1. The confidence level (cc) is 0.95.
2. The sample standard deviation (ss) is 4.
3. The sample size (nn) is 8.
4. The margin of error is calculated using the formula for a t-distribution, as the population standard deviation is unknown and the sample size is small (n<30n < 30).
5. The margin of error formula for a t-distribution is given by: E=tα2sn E = t_{\frac{\alpha}{2}} \cdot \frac{s}{\sqrt{n}} where tα2t_{\frac{\alpha}{2}} is the t-score that corresponds to the confidence level and degrees of freedom (df=n1df = n - 1), ss is the sample standard deviation, and nn is the sample size.

STEP 2

Determine the degrees of freedom for the t-distribution.
df=n1 df = n - 1

STEP 3

Plug in the value of nn to find the degrees of freedom.
df=81=7 df = 8 - 1 = 7

STEP 4

Determine the value of α\alpha (alpha), which is the probability in the tails (the complement of the confidence level).
α=1c \alpha = 1 - c

STEP 5

Plug in the value of cc to find α\alpha.
α=10.95=0.05 \alpha = 1 - 0.95 = 0.05

STEP 6

Since the t-distribution is symmetric, the probability in each tail is α2\frac{\alpha}{2}.
α2=0.052=0.025 \frac{\alpha}{2} = \frac{0.05}{2} = 0.025

STEP 7

Find the t-score (tα2t_{\frac{\alpha}{2}}) that corresponds to the given confidence level and degrees of freedom. This is typically done using a t-distribution table or a calculator with statistical functions.

STEP 8

For a confidence level of 0.95 and 7 degrees of freedom, the t-score is approximately 2.365 (this value may vary slightly depending on the t-distribution table or calculator used).

STEP 9

Now that we have the t-score, we can calculate the margin of error using the formula.
E=tα2sn E = t_{\frac{\alpha}{2}} \cdot \frac{s}{\sqrt{n}}

STEP 10

Plug in the values for tα2t_{\frac{\alpha}{2}}, ss, and nn to calculate the margin of error.
E=2.36548 E = 2.365 \cdot \frac{4}{\sqrt{8}}

STEP 11

Calculate the square root of nn.
8=2.8284 \sqrt{8} = 2.8284

STEP 12

Now, divide the sample standard deviation by the square root of the sample size.
42.82841.4142 \frac{4}{2.8284} \approx 1.4142

STEP 13

Multiply the t-score by the result from the previous step to find the margin of error.
E=2.3651.4142 E = 2.365 \cdot 1.4142

STEP 14

Calculate the margin of error.
E2.3651.41423.344 E \approx 2.365 \cdot 1.4142 \approx 3.344
The margin of error for the given values of cc, ss, and nn is approximately 3.344.

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