A lumber yard has scrap wood for sale. One employee recorded the measurements for the lengths of 50 different wood boards. The m
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The confidence interval is from 9.81 to 10.19.
We first find the mean of the data:
<span>(9.8+10.2+10.4+9.8+10.0+10.2+9.6)/7 = 10
Next we find the standard deviation:
</span>σ=√([<span>(9.8-10)^2+(10.2-10)^2+(10.4-10)^2+(9.8-10)^2+(10-10)^2+(10.2-10)^2+(9.6-10)^2]/7) = 0.262
The z-score for 95% confidence is found by
1-0.95 = 0.05; 0.05/2 = 0.025; from the z-table, it is 1.96.
The confidence interval is calculated using
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<span>
</span>
We first find the mean of the data:
<span>(9.8+10.2+10.4+9.8+10.0+10.2+9.6)/7 = 10
Next we find the standard deviation:
</span>σ=√([<span>(9.8-10)^2+(10.2-10)^2+(10.4-10)^2+(9.8-10)^2+(10-10)^2+(10.2-10)^2+(9.6-10)^2]/7) = 0.262
The z-score for 95% confidence is found by
1-0.95 = 0.05; 0.05/2 = 0.025; from the z-table, it is 1.96.
The confidence interval is calculated using
</span>
</span>