Author Question: Suppose the amount of propane used per customer in a month is normally distributed with . Find a ... (Read 176 times)

Starlight · **on:** Jun 24, 2018

Suppose the amount of propane used per customer in a month is normally distributed with

. Find a 95 confidence interval for

if a randomly chosen sample of 30 customers has a mean propane usage of 110 gallons a month.

a.(78.6, 141.4)
b.(105.2, 114.8)
c.(103.2, 116.8)
d.(104.3, 115.7)

Question 2

Which of the following is not a correct statement with regards to estimating a mean

using a known

?

a.If the sampling distribution for sample means

has a mean equal to

and a standard error equal to

and the randomly sampled population is normally distributed, then the sampling distribution of

has a normal distribution.
b.The sampling distribution of

is normally distributed only if the sampled population is normally distributed.
c.A necessary assumption for estimating a mean

using a known

is that the sampling distribution of

is normally distributed.
d.If the sampling distribution for sample means

has a mean equal to

and a standard error equal to

and the randomly sampled population is not normally distributed, then the sampling distribution of

is approximately normally distributed only for sufficiently large sample sizes.

cascooper22 · **Reply #1 on:** Jun 24, 2018

Answer to Question 1

correct: d

Answer to Question 2

correct: b

Starlight · **Reply 2 on:** Jun 24, 2018

Excellent

nguyenhoanhat

Great answer, keep it coming