Question

Allen's hummingbird (*Selasphorus sasin*) has been
studied by zoologist Bill Alther.† Suppose a small group of 12
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is *x* = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with *σ* = 0.22
gram.

Find the sample size necessary for an 80% confidence level with a
maximal margin of error *E* = 0.16 for the mean weights of
the hummingbirds. (Round up to the nearest whole number.)

Answer #1

Solution :

Given that,

standard deviation = =0.22

Margin of error = E = 0.16

At 80% confidence level the z is ,

= 1 - 80% = 1 - 0.80 = 0.20

/ 2 =0.10

Z/2 = Z0.10= 1.28 Using z table )

sample size = n = [Z/2* / E] 2

n = ( 1.28*0.22 /0.16 )2

n =3.0976

Sample size = n =3

Allen's hummingbird (Selasphorus sasin) has been studied by
zoologist Bill Alther.† Suppose a small group of 14 Allen's
hummingbirds has been under study in Arizona. The average weight
for these birds is x = 3.15 grams. Based on previous studies, we
can assume that the weights of Allen's hummingbirds have a normal
distribution, with σ = 0.26 gram.
(d) Find the sample size necessary for an 80% confidence level
with a maximal margin of error E = 0.06 for the
mean...

Allen's hummingbird (Selasphorus sasin) has been studied by
zoologist Bill Alther.† Suppose a small group of 17 Allen's
hummingbirds has been under study in Arizona. The average weight
for these birds is x = 3.15 grams. Based on previous studies, we
can assume that the weights of Allen's hummingbirds have a normal
distribution, with σ = 0.20 gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 19
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with ? = 0.22
gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. (Round your answers to
two...

Allen's hummingbird (Selasphorus sasin) has been studied by
zoologist Bill Alther.† Suppose a small group of 18 Allen's
hummingbirds has been under study in Arizona. The average weight
for these birds is x = 3.15 grams. Based on previous studies, we
can assume that the weights of Allen's hummingbirds have a normal
distribution, with σ = 0.28 gram. (a) Find an 80% confidence
interval for the average weights of Allen's hummingbirds in the
study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 12
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with σ = 0.34
gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been studied by
zoologist Bill Alther.† Suppose a small group of 16 Allen's
hummingbirds has been under study in Arizona. The average weight
for these birds is x = 3.15 grams. Based on previous studies, we
can assume that the weights of Allen's hummingbirds have a normal
distribution, with σ = 0.32 gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 10
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with σ = 0.26
gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 18
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with ? = 0.20
gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 20
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with σ = 0.30
gram.
a.) When finding an 80% confidence interval, what is the
critical value for confidence level? (Round your answers to two
decimal places.)...

Allen's hummingbird (Selasphorus sasin) has been
studied by zoologist Bill Alther.† Suppose a small group of 10
Allen's hummingbirds has been under study in Arizona. The average
weight for these birds is x = 3.15 grams. Based on
previous studies, we can assume that the weights of Allen's
hummingbirds have a normal distribution, with σ = 0.22
gram.
(a) Find an 80% confidence interval for the average weights of
Allen's hummingbirds in the study region. What is the margin of...

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