Pregunta 4 (1 punto)
2 answers:
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Answer:
Probability that the average length of a sheet is between 30.25 and 30.35 inches long is 0.0214 .
Step-by-step explanation:
We are given that the population of lengths of aluminum-coated steel sheets is normally distributed with a mean of 30.05 inches and a standard deviation of 0.2 inches.
Also, a sample of four metal sheets is randomly selected from a batch.
Let X bar = Average length of a sheet
The z score probability distribution for average length is given by;
Z = ~ N(0,1)
where, = population mean = 30.05 inches
= standard deviation = 0.2 inches
n = sample of sheets = 4
So, Probability that average length of a sheet is between 30.25 and 30.35 inches long is given by = P(30.25 inches < X bar < 30.35 inches)
P(30.25 inches < X bar < 30.35 inches) = P(X bar < 30.35) - P(X bar <= 30.25)
P(X bar < 30.35) = P( <
) = P(Z < 3) = 0.99865
P(X bar <= 30.25) = P( <=
) = P(Z <= 2) = 0.97725
Therefore, P(30.25 inches < X bar < 30.35 inches) = 0.99865 - 0.97725
= 0.0214
Answer:
a) (1215, 1297)
b) (1174, 1338)
c) (1133, 1379)
Step-by-step explanation:
We are given the following information in the question:
Mean, μ = 1256
Standard Deviation, σ = 41
Empirical Rule:
- Also known as 68-95-99.7 rule.
- It states that almost all the data lies within three standard deviation for a normal data.
- About 68% of data lies within 1 standard deviation of mean.
- About 95% of data lies within two standard deviation of mean.
- About 99.7% of data lies within 3 standard deviation of mean.
a) range of years centered about the mean in which about 68% of the data lies
68% of data will be found between 1215 years and 1297 years.
b) range of years centered about the mean in which about 95% of the data lies
95% of data will be found between 1174 years and 1338 years.
c) range of years centered about the mean in which about all of the data lies
All of data will be found between 1133 years and 1379 years.