In metal fabrication unit, steel rods of a particular type have lengths with standard deviation 0.01 in. (a) Assume that the lengths are normally distributed with mean and specifications on this length are 33.7 in. +0.025 in.. What fraction of the lengths of rods actually satisfy this specification, if µ = 33.7 in.? fraction = (Round your answer to three decimal places.) (b) If lengths are normally distributed with a mean of 33.69 in. (and same standard deviation as above), evaluate the probability that at least 8 of the next 10 steel rods produced are within the specifications of 33.7 in. + 0.025 in.. probability = (Round your answer to three decimal places.) (c) Let š denote the sample mean length of 64 rods of this type. Approximate the probability that is X within 0.001 in. of H. probability = (Round your answer to three decimal places.)

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In metal fabrication unit, steel rods of a particular type have lengths with
standard deviation 0.01 in.
(a) Assume that the lengths are normally distributed with mean u and
specifications on this length are 33.7 in. + 0.025 in.. What fraction
of the lengths of rods actually satisfy this specification, if u = 33.7
in.?
fraction =
(Round your answer to three
decimal places.)
(b) If lengths are normally distributed with a mean of 33.69 in. (and
same standard deviation as above), evaluate the probability that at
least 8 of the next 10 steel rods produced are within the
specifications of 33.7 in. + 0.025 in..
probability =
(Round your answer to three
decimal places.)
(c) Let x denote the sample mean length of 64 rods of this type.
Approximate the probability that is X within 0.001 in. of H.
probability =
(Round your answer to three
decimal places.)
Transcribed Image Text:In metal fabrication unit, steel rods of a particular type have lengths with standard deviation 0.01 in. (a) Assume that the lengths are normally distributed with mean u and specifications on this length are 33.7 in. + 0.025 in.. What fraction of the lengths of rods actually satisfy this specification, if u = 33.7 in.? fraction = (Round your answer to three decimal places.) (b) If lengths are normally distributed with a mean of 33.69 in. (and same standard deviation as above), evaluate the probability that at least 8 of the next 10 steel rods produced are within the specifications of 33.7 in. + 0.025 in.. probability = (Round your answer to three decimal places.) (c) Let x denote the sample mean length of 64 rods of this type. Approximate the probability that is X within 0.001 in. of H. probability = (Round your answer to three decimal places.)
Expert Solution
Step 1

a)

The Z-score of a random variable X is defined as follows:

Z = (Xµ)/σ.

Here, µ and σ are the mean and standard deviation of X, respectively.

Step 2

Consider a random variable X that is the length of steel rod.

According to the given information X follows normal distribution with mean μ = 33.7 in and standard deviation of σ = 0.01 in.

The proportion of lengths of rods actually satisfy this specification of 33.7 ± 0.025 is,

Statistics homework question answer, step 2, image 1

Thus, the fraction of lengths of rods actually satisfy this specification of 33.7 ± 0.025 is 0.988.

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