Question

Johnson Electronics Corporation makes electric tubes. It is known that the standard deviation of the lives of these tubes is 135 hours. The company’s research department takes a sample of 105 such tubes and finds that the mean life of these tubes is 2150 hours. What is the probability that this sample mean is within 20 hours of the mean life of all tubes produced by this company?

Round your answer to four decimal places.

P=___

Answer #1

Here, μ = 2150, σ = 135/sqrt(105) = 13.1747, x1 = 2130 and x2 = 2170. We need to compute P(2130<= X <= 2170). The corresponding z-value is calculated using Central Limit Theorem

z = (x - μ)/σ

z1 = (2130 - 2150)/13.1747 = -1.52

z2 = (2170 - 2150)/13.1747 = 1.52

Therefore, we get

P(2130 <= X <= 2170) = P((2170 - 2150)/13.1747) <= z <=
(2170 - 2150)/13.1747)

= P(-1.52 <= z <= 1.52) = P(z <= 1.52) - P(z <=
-1.52)

= 0.9357 - 0.0643

= 0.8714

Future Electronics makes compact disc players. Its research
department found that the life of the laser beam device is normally
distributed, with mean 5020 hours and standard deviation 400
hours.
(a) Find the probability that the laser beam device will wear
out in 5000 hours or less. (Round your answer to four decimal
places.)
(b) Future Electronics wants to place a guarantee on the players so
that no more than 4% fail during the guarantee period. Because the
laser pickup...

Future Electronics makes compact disc players. Its research
department found that the life of the laser beam device is normally
distributed, with mean 4740 hours and standard deviation 460
hours.
(a) Find the probability that the laser beam device will wear
out in 5000 hours or less. (Round your answer to four decimal
places.)
(b) Future Electronics wants to place a guarantee on the players so
that no more than 10% fail during the guarantee period. Because the
laser pickup...

Future Electronics makes compact disc players. Its research
department found that the life of the laser beam device is normally
distributed, with mean 5020 hours and standard deviation 450
hours.
(a) Find the probability that the laser beam device will wear
out in 5000 hours or less. (Round your answer to four decimal
places.)
_______
(b) Future Electronics wants to place a guarantee on the players so
that no more than 10% fail during the guarantee period. Because the
laser...

Future Electronics makes compact disc players. Its research
department found that the life of the laser beam device is normally
distributed, with mean 4940 hours and a standard deviation of 480
hours.
(a) Find the probability that the laser beam device will wear
out in 5000 hours or less.
(b) Future Electronics wants to place a guarantee on the players
so that no more than 13% fail during the guarantee period. Because
the laser pickup is the part most likely...

Lazurus Steel Corporation produces iron rods that are supposed
to be 36 inches long. The machine that makes these rods does not
produce each rod exactly 36 inches long. The lengths of the rods
are normally distributed and vary slightly. It is known that when
the machine is working properly, the mean length of the rods is 36
inches. The standard deviation of the lengths of all rods produced
on this machine is always equal to 0.035 inch. The quality...

Lazurus Steel Corporation produces iron rods that are supposed
to be 36 inches long. The machine that makes these rods does not
produce each rod exactly 36 inches long. The lengths of the rods
are normally distributed and vary slightly. It is known that when
the machine is working properly, the mean length of the rods is 36
inches. The standard deviation of the lengths of all rods produced
on this machine is always equal to 0.035 inch. The quality...

1) The average life of light bulbs produced by SABA Electric Co.
is expected to be normally distributed with the mean service life
of 850 hours and a standard deviation of 100 hours. A random sample
of 144 bulbs is tested and it has a mean life of 920 hours. Can it
be concluded that the mean service life of the bulbs is more than
the expectation at significant level of 0.02? 1) Which method
researcher can use to check...

1. According to the Bureau labor of statistics, the mean weekly
earnings for people working in a sales-related profession in 2010
was $660. Assume the weekly earnings are approximately normally
distributed with a standard deviation of $75. If a salesperson was
randomly selected, find the probability that his or her weekly
earnings are at most $40.(choose the best answer)
a. .0004
b. .4246
c. .0478
d. .4182
e. .6255
2. A film distribution manager calculates that 8% of the films...

1. Find the area under the standard normal curve (round to four
decimal places)
a. To the left of z=1.65
b. To the right of z = 0.54
c. Between z = -2.05 and z = 1.05
2. Find the z-score that has an area of 0.23 to its right.
3. The average height of a certain group of children is 49
inches with a standard deviation of 3 inches. If the heights are
normally distributed, find the probability that a...

2. SECURING THE WORKFORCE Diversity management in
X-tech, a Japanese organisation
This case is intended to be used as a basis for class discussion
rather than as an illustration of the effective or ineffective
handling of an administrative situation. The name of the company is
disguised.
INTRODUCTION
In light of demographic concerns, in 2012, the Japanese
government initiated an effort to change the work environment in
order to secure the workforce of the future. Japan is world
renowned for its...

ADVERTISEMENT

Get Answers For Free

Most questions answered within 1 hours.

ADVERTISEMENT

asked 6 minutes ago

asked 12 minutes ago

asked 15 minutes ago

asked 15 minutes ago

asked 29 minutes ago

asked 33 minutes ago

asked 36 minutes ago

asked 44 minutes ago

asked 51 minutes ago

asked 1 hour ago

asked 1 hour ago

asked 1 hour ago