Question

A random sample of 99 light bulbs had a mean life of x = 415 hours with a standard deviation of a = 34 hours. Construct a 90% confidence interval for the mean life, μ, of all light bulbs of this type. Round to the nearest ones place?

Answer #1

A random sample of 12 light bulbs has a mean life of 1421 hours
with a standard deviation of 68 hours. Construct a 95% confidence
interval for the mean life, μ, of all light bulbs of this
type. Assume the population has a normal distribution.
Group of answer choices
(1378.2, 1463.8)
(1383.7, 1458.3)
(1382.5, 1459.5)
(1377.8, 1464.2)
(1381.7, 1460.2)

A
random Sample of 79 light bulbs had a mean Iife of 400 hours with
standard deviation of 28 hours. Construct 90% interval for the mean
life of light bulbs

The quality control manager at a light bulb factory needs to
estimate the mean life of a large shipment of light bulbs. The
standard deviation is 98 hours. A random sample of 49 light bulbs
indicated a sample mean life of 300 hours.
(a) Construct a 99% confidence interval estimate for the
population mean life of light bulbs in this shipment.
(Ans.) The 99% confidence interval estimate is from a lower
limit of 263.9 hours to an upper limit of...

1. The quality control manager at a light-bulb factory needs to
estimate the mean life of a new type of light-bulb. The population
standard deviation is assumed to be 45 hours. A random sample of 37
light-bulbs shows a sample mean life of 470 hours. Construct and
explain a 99% confidence interval estimate of the population mean
life of the new light-bulb.

The quality control manager at a light-bulb factory
needs to estimate the mean life of a new type of light-bulb. The
population standard deviation is assumed to be 50 hours. A random
sample of 35 light-bulbs shows a sample mean life of 490 hours.
Construct and explain a 90% confidence interval estimate of the
population mean life of the new light-bulb. What size sample would
be needed to achieve a margin of error of 15 hours or less? Show
all...

In a sample of 80 light bulbs, the mean lifetime was 1217 hours
with a standard deviation of 53 hours.
Find a 90% upper confidence interval for the mean lifetime.
(Round the final answer to two decimal places.)
The 90% upper confidence bound is ____
I got 1226.75, but it says it incorrect.

The quality control manager at a light bulb factory needs to
estimate the mean life of a large shipment of light bulbs. The
standard deviation is 104 hours. A random sample of 64 light bulbs
indicated a sample mean life of 390 hours. Complete parts (a)
through (d) below.
Construct a 99 % confidence interval estimate for the population
mean life of light bulbs in this shipment.
c. Must you assume that the population light bulb life is
normally distributed?...

An electrical firm manufactures light bulbs that have a length
of life that is normally distributed, with mean equal to 800 hours
and a standard deviation of 40 hours. Suppose a 100 light bulbs are
randomly selected for testing the length of life. Let x ̅ represent
the sample mean length of life of the light bulbs.
σ_( x ̅ ) = 4 hours
n) Find a lower and an upper mean length of life of bulbs in
hours such...

There is a large supply of light bulbs with the
average life of 1000 hours and the standard
deviation of 50 hours.
A light bulb is drawn at random. Find the probability that it
will last more than 1020 hours.
A random sample of 25 light bulbs is drawn.
Find the probability that the sample average life
is more than 1020 hours.
Using Ti-34 calculator
Equations/answer written out using
binomcdf(x,x,x)
Binompdf(x,x,x)
Invnorm
InvT
tcdf
If possible/needed to solve the equation

an electrical firm manufactures light bulbs that have a length
of life that is approximately normally distributed with a standard
deviation of 40 hours. the firm claims that the mean life of the
light bulb is 800 hrs
a?if a sample of 30 light bulbs were tested to failure and had
an avg life of 780 hours, find 90% confidence interval on the
mean
b) based on this confidence interval, would you be able to
validate the claimed mean life...

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