1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
galben [10]
3 years ago
11

The lifetime (in hours) of a 60-watt light bulb is a random variable that has a Normal distribution with σ = 30 hours. A random

sample of 25 bulbs put on test produced a sample mean lifetime of = 1038 hours. If in the study of the lifetime of 60-watt light bulbs it was desired to have a margin of error no larger than 6 hours with 99% confidence, how many randomly selected 60-watt light bulbs should be tested to achieve this result?
Physics
1 answer:
attashe74 [19]3 years ago
5 0

Answer:

They must have about 166 randomly 60 watt light bulbs to achieve the result

N = 166

Explanation:

σ = 30

% 99 = 2.576

Using the standard equation of statistics knowing the difference between the measurement have a margin error no larger than 6 can solve

σ = √∑ ( x - z' )²  / N

Solve to N

N = ( % * σ  / Δ x  ) ²

N = ( 2.576 * 30 / 6 )²

N = 12.88 ²

N = 165. 89 44 ≅ 166

You might be interested in
You are in a boat that is 1400 kg. The current is 1500N and is pushing you back. If you have an acceleration of 3 m/s^2 what is
aleksandrvk [35]

Answer: The force of the engines is 5700N

Explanation:

By the second Newton's law, we have that:

F = m*a

Force equals mass times acceleration.

In this case, we have:

m = 1400kg

a = 3 m/s^2

And the force will be equal to the force of the engines, f, plus the force of  the current, -1500 N (because this is pushing you back, so it is in the opposite direction than f), then we have:

F = f - 1500N

Then we have the equation:

f - 1500N = 1400kg*3m/s^2 = 4200N

f - 1500N = 4200N

f = 4200N + 1500N = 5700N

The force of the engines is 5700N

5 0
2 years ago
To water the yard you use a hose with a diameter of 3.2 cm. Water flows from the hose with a speed of 1.1 m/s. If you partially
cupoosta [38]

Answer:

The speed of water flow inside the pipe at point - 2 = 34.67 m / sec

Explanation:

Given data

Diameter at point - 1 = 3.2 cm

Velocity at point - 1 = 1.1 m / sec = 110 cm / sec

Diameter at point - 2 = 0.57 cm

Velocity at point - 2 = ??

We know that from the continuity equation the rate of flow is constant inside  a pipe between two points.

Thus

⇒ A_{1} × V_{1} = A_{2} × V_{2}

⇒  \frac{\pi }{4} × d_{1} ^{2} × V_{1} =

⇒  d_{1} ^{2} × V_{1} =  d_{2} ^{2}  × V_{2}

⇒  (3.2)^{2} × 110 = (0.57)^{2} × V_{2}

⇒ V_{2} = 3467 cm / sec

⇒ V_{2} = 34.67 m / sec  

Thus the speed of water flow inside the pipe at point - 2 = 34.67 m / sec

3 0
3 years ago
A storage tank containing oil (SG=0.92) is 10.0 meters high and 16.0 meters in diameter. The tank is closed, but the amount of o
blagie [28]

Answer:

a-1 Graph is attached. The relation is linear.

a-2 The corresponding height for 68 kPa Pressure is 7.54 m

a-3 The corresponding weight for 68 kPa Pressure is 1394726kg

b The original height of the column is 5.98 m

Explanation:

Part a

a-1

The graph is attached with the solution. The relation is linear as indicated by the line.

a-2

By the equation

P=\rho \times g \times h

Here

  • P is the pressure which is given as 68 kPa.
  • ρ is the density of the oil whose SG is 0.92. It is calculated as

                                       \rho=S.G \times \rho_{water}\\\rho=0.92 \times 1000 kg/m^3\\\rho=920 kg/m^3\\

  • g is the gravitational constant whose value is 9.8 m/s^2
  • h is the height which is to be calculated

                                        P=\rho \times g \times h\\h=\frac{P}{\rho \times g}\\h=\frac{68 \times 10^3}{920 \times 9.8}\\h=7.54m

So the height of column is 7.54m

a-3

By the relation of volume and density

M=\rho \times V

Here

  • ρ is the density of the oil which is 920 kg/m^3
  • V is the volume of cylinder with diameter 16m calculated as follows

                             V=\pi r^2h\\V=3.14\times (8)^2 \times 7.54\\V=1515.23 m^3

Mass is given as

                             M=\rho \times V\\M=920 \times 1515.23\\M=1394726kg

So the mass of oil leading to 68kPa is 1394726kg

Part b

Pressure variation is given as

                            \Delta P=P_{obs}-P_{atm}\\\Delta P=115-101 kPa\\\Delta P=14 kPa\\

Now corrected pressure is as

P_c=P_g-\Delta P\\P_c=68-14 kPa\\P_c=54 kPa

Finding the value of height for this corrected pressure as

P_c=\rho \times g \times h\\h=\frac{P_c}{\rho \times g}\\h=\frac{54 \times 10^3}{920 \times 9.8}\\h=5.98m

The original height of column is 5.98m

4 0
3 years ago
Distance meters Time (seconds) Trial Tria 2 Trials Average 3 053 059 0.52 055 6 106 719 104 Uning the values trom the data table
kumpel [21]
Jsisisusuagahannananana this is worth 22 points g that’s crazy 25
5 0
2 years ago
Fl-19 in florida, if your pwc is equipped with an engine cut-off lanyard, what must you do with it?
melamori03 [73]

Answer: Attach it to clothing, personal flotation device or the person's person.

Explanation:

This particular Question or problem has to do with the rules and regulations or laws governing the use of Personal Watercraft(PWC) in the state of Florida in the United States of America. Hence, one of the rules that is applicable to the use of boats and waterways or the use of personal watercraft in Florida is that in florida, if ones pwc is equipped with an engine cut-off lanyard the person operating it must ATTACH IT TO THE CLOTHING, PERSONAL FLOATATION DEVICE IR THE OPERATORS' PERSON.

Another rule band the use of flammable personal flotation device with Personal Watercraft(PWC) in the state of Florida. All this rules and guildlines are made to limit or minimize hazards.

3 0
3 years ago
Other questions:
  • A large crate sits on the floor of a warehouse. Paul and Bob apply constant horizontal forces to the crate. The force applied by
    8·1 answer
  • Isaac Newton’s investigations of gravity explained which of the following?
    13·2 answers
  • You come across an open container which is filled with two liquids. Since the two liquids have different density there is a dist
    12·1 answer
  • When 0.250 moles of licl are added to 200.0g of water in a constant pressure?
    12·1 answer
  • A boat is moving along the water. The forward thrust from the engines is 35,000 N. Water resistance is 20,000 N and air resistan
    10·1 answer
  • If 5 C of charge flow past a given point in a circuit in 10 seconds, then the current is _________ A.
    12·1 answer
  • When a hypothesis is wrong, scientists often begin by revising the (blank)
    12·2 answers
  • A handbag weighing 162 N is carried by two students each holding the handle of the bag
    14·1 answer
  • When a speeding truck hits a stationary car, the car is deformed and heat is generated. What can you say about the kinetic energ
    10·1 answer
  • A mass m is attached to an ideal massless spring. When this system is set in motion with amplitude a, it has a period t. What is
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!