Estimate and then find the sum
2 answers:
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Answer:
the probability of no defects in 10 feet of steel = 0.1353
Step-by-step explanation:
GIven that:
A roll of steel is manufactured on a processing line. The anticipated number of defects in a 10-foot segment of this roll is two.
Let consider β to be the average value for defecting
So;
β = 2
Assuming Y to be the random variable which signifies the anticipated number of defects in a 10-foot segment of this roll.
Thus, y follows a poisson distribution as number of defect is infinite with the average value of β = 2
i.e
the probability mass function can be represented as follows:
where;
y = 0,1,2,3 ...
Hence, the probability of no defects in 10 feet of steel
y = 0
P(y =0) = 0.1353
Answer:
The new sample size required in order to have the same confidence 95% and reduce the margin of erro to $60 is:
n=28
Step-by-step explanation:
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Assuming the X follows a normal distribution
And the distribution for is:
We know that the margin of error for a confidence interval is given by:
(1)
The next step would be find the value of ,
and
Using the normal standard table, excel or a calculator we see that:
If we solve for n from formula (1) we got:
And we have everything to replace into the formula:
And this value agrees with the sample size given.
For the case of the problem we ar einterested on Me= $60, and we need to find the new sample size required to mantain the confidence level at 95%. We know that n is given by this formula:
And now we can replace the new value of Me and see what we got, like this:
And if we round up the answer we see that the value of n to ensure the margin of error required $ is n=28.