Question

The *ideal* (daytime) noise-level for hospitals is 45
decibels with a standard deviation of 12 db; which is to say,
*this may not be true*. A simple random sample of 75
hospitals at a moment during the day gives a mean noise level of 47
db. Assume that the standard deviation of noise level for all
hospitals is really 12 db. All answers to two places after the
decimal.

(a) A 99% confidence interval for the actual mean noise level in
hospitals is db, db).

(b) We can be 90% confident that the actual mean noise level in hospitals is db with a margin of error of db.

(c) Unless our sample (of 81 hospitals) is among the most unusual 2% of samples, the actual mean noise level in hospitals is between db and db.

(d) A 99.9% confidence interval for the actual mean noise level in hospitals is db, db).

(e) Assuming our sample of hospitals is among the most typical half of such samples, the actual mean noise level in hospitals is between db and db.

(f) We are 95% confident that the actual mean noise level in hospitals is db, with a margin of error of db.

(g) How many hospitals must we examine to have 95% confidence that we have the margin of error to within 0.5 db?

(h) How many hospitals must we examine to have 99.9% confidence that we have the margin of error to within 0.5 db?

Answer #1

The ideal (daytime) noise-level for hospitals is 45
decibels with a standard deviation of 11 db; which is to say,
this may not be true. A simple random sample of 80
hospitals at a moment during the day gives a mean noise level of 47
db. Assume that the standard deviation of noise level for all
hospitals is really 11 db. All answers to two places after the
decimal.
(a) A 99% confidence interval for the actual mean noise level...

The ideal (daytime) noise-level for hospitals is 45 decibels
with a standard deviation of 10 db; which is to say, this may not
be true. A simple random sample of 70 hospitals at a moment during
the day gives a mean noise level of 47 db. Assume that the standard
deviation of noise level for all hospitals is really 10 db. All
answers to two places after the decimal.(e) Assuming our sample of
hospitals is among the most typical half...

The ideal (daytime) noise-level for hospitals is 45 decibels
with a standard deviation of 10 db. A simple random sample of 500
hospitals at a moment during the day gives a mean noise level of 46
db. Assume that the standard deviation of noise level is really 10
db.
Part One.
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5. Mean of 1500, standard deviation of 300. Estimating the
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6. Population proportion is 43%, would like to be 95% confident
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During a blood-donor program conducted during finals week for
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