Question

an agricultural researcher takes a simple random sample of 400 English carrot farms. for the sample she finds that 120 of the farms require irrigation in two of the farms have over 100 acres. which of the following is an approximate 99% confidence interval for the percentage of farms that require irrigation?

a. 24% to 36%

b. 25% to 35%

c. 26% to 34%

d. a 99% confidence interval is not possible only 90%
and 95% confidence intervals are possible

2. which of the following is an approximate 90% confidence interval for the percentage of farms that have over 100 acres?

a. 0.2% to 1.8%

b. .1% to 1.1%

c. 26% to 34%

d. a 90% confidence interval is not possible only 95% and 99% confidence intervals are possible

Answer #1

A simple random sample of 70 items from a population with = 8
resulted in a sample mean of 34.
If required, round your answers to two decimal places.
a. Provide a 90% confidence interval for the
population mean.
to
b. Provide a 95% confidence interval for the
population mean.
to
c. Provide a 99% confidence interval for the
population mean.

A simple random sample of 60 items from a population with
σ = 8
resulted in a sample mean of 34. (Round your answers to two
decimal places.)
A. Provide a 90% confidence interval for the population
mean.
B. Provide a 95% confidence interval for the population
mean.
C.Provide a 99% confidence interval for the population mean.

2. A survey organization takes a simple random sample of 200
households from a city of 50,000 households. On the average there
are 2.3 persons per sample household, and the SD is 1.8.
a) Find a 90%-confidence interval for the average household size
in the city
b) Find a 80%-confidence interval for the average household size
in the city.
c) If the researcher decreased the sample size to only 50
people, the length of the 80% confidence interval would be:...

A survey organization takes a simple random sample
of 200 households from a city of 50,000 households. On
the average there are 2.3 persons per sample household,
and the SD is 1.8.
a) Find a 90%-confidence interval for the average
household size in the city
b) Find a 80%-confidence interval for the average
household size in the city.
c) If the researcher decreased the sample size to
only 50 people, the length of the 80% confidence
interval would be:
(i) multiplied by
2 (ii)multiplied by
4 (iii)
divided by...

Note: Each bound should be rounded to three decimal places.
A random sample of ?=100 observations produced a mean of
?=26 with a standard deviation of ?=5
(a) Find a 99% confidence interval for ?
Lower-bound:___ Upper-bound:___
(b) Find a 90% confidence interval for ?
Lower-bound:___ Upper-bound:___
(c) Find a 95% confidence interval for ?
Lower-bound: ___ Upper-bound:____

Suppose that a random sample of 50 bottles of a particular brand
of cough syrup is selected and the alcohol content of each bottle
is determined. Let μ denote the average alcohol content for the
population of all bottles of the brand under study. Suppose that
the resulting 95% confidence interval is (7.6, 9.2). (a) Would a
90% confidence interval calculated from this same sample have been
narrower or wider than the given interval? Explain your reasoning.
The 90% would...

In a simple random sample of 1180 U.S. adults from a large
population, it is found that 816 “regularly” spend more than 40
minutes per day checking email. Use this sample to estimate the
true percentage, p, of all U.S. adults in this population who
“regularly” spend more than 40 minutes per day checking email.In
each question below, give answers as percents, rounded to at least
two decimal places.
(a) Find a 95% confidence interval for p
% < p...

A random sample of 10 drivers reported the below average mileage
in the city for their cars.
18, 21, 24, 25, 25, 25, 25, 26, 29, & 31
The mean of the sample is 24.9 miles per gallon, with an
associated standard deviation of about 3.6.
Find the 95% confidence interval for the average mileage of the
cars for all of the drivers in the class. Assume all normality
conditions apply.
Determine the approximate sample size needed to estimate the...

Question 6
A random sample of 13 DVD movies had a mean length of 115.1
minutes, with a standard deviation of 64.7 minutes. Find the lower
bound of the 90% confidence interval for the true mean length of
all Hollywood movies. Assume movie lengths to be approximately
normally distributed.
Round to one decimal place (for example: 108.1). Write only a
number as your answer. Do not write any units.
Question 7
Six measurements were made of the mineral content (in...

The diameters of a random sample of 20 products made by a
certain machine during one month showed a mean of 0.93 inch and a
sample standard deviation of 0.05 inch. Assume the population is
normally distributed, find a 95% confidence intervals for the mean
diameter of all the products.
Select one:
a. 0.9066 to 0.9534 inch
b. 0.9081 to 0.9519 inch
c. 0.9248 to 0.9352 inch
d. 0.9107 to 0.9493 inch
“Is live lecture over Zoom an effective way...

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