Help please I don’t get it
1 answer:
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Answer:
a
b
Step-by-step explanation:
From the question we are told that
The mean value is
The standard deviation is
Considering question a
The sample size is n = 9
Generally the standard error of the mean is mathematically represented as
=>
=>
Generally the probability that the sample mean hardness for a random sample of 9 pins is at least 51 is mathematically represented as
=>
From the z table the area under the normal curve to the left corresponding to 2.5 is
=>
=>
Considering question b
The sample size is n = 40
Generally the standard error of the mean is mathematically represented as
=>
=>
Generally the (approximate) probability that the sample mean hardness for a random sample of 40 pins is at least 51 is mathematically represented as
=>
=>
From the z table the area under the normal curve to the left corresponding to 5.2715 and
=>
So
=>