The compressive strength of concrete is being tested by a civil engineer who tests 12 specimens and finds that the sample mean i
1 answer:
Answer:
The 95% confidence interval for mean compressive strength is:
Step-by-step explanation:
We have a sample of n=12 specimens, with sample mean=3259.9 and sample standard deviation = 35.57.
We know the population is normally distributed.
For a 95% confidence interval and df=n-1=11, the t-statistic is t=2.201.
Then, the CI can be expressed as:
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The ratio of the model's height to actual height of tower is 1:725
Step-by-step explanation:
Given
Actual height of Sears Tower = = 1450 feet
Height of Model = = 24 inches
We can divide the actual height by the model's height to find the scale
Let z be the ratio of the height of the model to the actual height
The ratio should be in same unit.
We know that
1 ft = 12 inches
Then
Hence,
The ratio of the model's height to actual height of tower is 1:725
Keywords: Ratios, models
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