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
Anit [1.1K]
3 years ago
14

If y varies inversely as x, and y =23 when x=8, find y when x=4

Engineering
1 answer:
serious [3.7K]3 years ago
4 0

Answer:

46

Explanation:

You might be interested in
"Transformer is used to change the voltage".
LUCKY_DIMON [66]

Hi! transformer is used to change the voltage through electromagnetic induction.

6 0
2 years ago
A civil engineer is analyzing the compressive strength of concrete. The compressive strength is approximately normal distributed
hram777 [196]

Answer:

See explanation

Explanation:

Solution:-

- A study on compressive strength of a concrete was made. The distribution of compressive strength ( experimental testing ) was normally distributed with variance ( σ^2 ).

- A random sample of n = 12 specimens were taken and the mean compressive strength ( μ ) of 3500 psi was claimed.

- We are to test the claim made by the civil engineer regarding the mean compressive strength of the concrete. The data of compressive strength of each specimen from the sample is given below:

            3273, 3229, 3256, 3272, 3201, 3247, 3267, 3237,

                          3286, 3210, 3265, 3273

- We will conduct the hypothesis whether the mean compressive strength of the concrete conforms to the claimed value.

      Null hypothesis: μ = 3500 psi

      Alternate hypothesis: μ ≠ 3500 psi

- The type of test performed on the sample data will depend on the application of Central Limit Theorem.

- The theorem states that the sample can be assumed to be normally distributed if drawn from a normally distributed population. ( We are given the population is normally distributed; hence, theorem applies )

- We will approximate the mean of the population ( μ ) with the sample mean ( x ), as per the implication specified by the theorem.

- The mean of the sample ( x ) is calculated as follows:

    x = \frac{Sum ( x_i )}{n} \\\\x = \frac{Sum ( 3273+ 3229+ 3256+ 3272+ 3201+ 3247+ 3267+ 3237+ 3286+ 3210+ 3265+3273 )}{12} \\\\x = \frac{39016}{12} \\\\x = 3251.3333

 

- Since, we are testing the average compressive strength of a concrete against a claimed value. Any value that deviates significantly from the claimed value is rejected. This corroborates the use of one sample two tailed test.

- The test value may be evaluated from either z or t distribution. The conditions for z-test are given below:

  • The population variance is known OR sample size ( n ≥ 30 )    

- The population variance is known; hence, we will use z-distribution to evaluate the testing value as follows:

              Z-test = \frac{x - u}{\sqrt{\frac{sigma^2}{n} } } \\\\Z-test = \frac{3251.333 - 3500}{\sqrt{\frac{1000^2}{12} } } \\\\Z-test = -27.24      

- The rejection region for the hypothesis is defined by the significance level ( α = 0.01 ). The Z-critical value ( limiting value for the rejection region ) is determined:

           Z-critical = Z_α/2 = Z_0.005

- Use the list of correlation of significance level ( α ) and critical values of Z to determine:

          Z-critical = Z_0.005 = ± 2.576

- Compare the Z-test value against the rejection region defined by the Z-critical value.

     Rejection region: Z > 2.576 or Z < -2.576

- The Z-test value lies in the rejection region:

            Z-test < Z-critical

           -27.24 < -2.576 .... Null hypothesis rejected

Conclusion: The claim made by the civil engineer has little or no statistical evidence as per the sample data available; hence, the average compressive strength is not 3500 psi.

- To construct a confidence interval for the mean compressive strength ( μ ) we need to determine the margin of error for the population.

- The margin of error (ME) is defined by the following formula:

              ME = Z^*. \frac{sigma}{\sqrt{n} }

Where,

- The ( Z* ) is the critical value for the defined confidence level ( CI ):

- The confidence interval and significance level are related and critical value Z* is as such:

   

            α = 1 - CI , Z* = Z_α/2

- The critical values for ( CI = 99% & 95% ) are evaluated:

           α = 1 - 0.99 = 0.01 , α = 1 - 0.95 = 0.05

           Z* = Z_0.005        ,   Z* = Z_0.025

           Z* = ± 2.58            ,   Z* = ± 1.96

- The formulation of Confidence interval is given by the following inequality:

                 [ x - ME  <    μ    <   x + ME ]

                 [ x - Z*√σ^2 / n   <    μ    <   x + Z*√σ^2 / n ]

- The CI of 95% yields:

   [ 3251.33 - 1.96*√(1000 / 12)   <    μ    <   3251.33 + 1.96*√(1000 / 12) ]

                [ 3251.333 - 17.89227 <    μ    <   3251.33 + 17.89227 ]

                              [ 3233.44  <    μ    <  3269.23  ]

- The CI of 99% yields:

   [ 3251.33 - 2.58*√(1000 / 12)   <    μ    <   3251.33 + 2.58*√(1000 / 12) ]

                [ 3251.333 - 23.552 <    μ    <   3251.33 + 23.552 ]

                              [ 3227.78  <    μ    <  3274.88  ]

                 

- We see that the width of the confidence interval increases as the confidence level ( CI ) increases. This is due to the increase in critical value ( Z* ) associated with the significance level ( α ) increases.    

7 0
3 years ago
Consider a steady-state experiment in which the observed current due to reduction of Ox to R is 85 mA/cm2. What is the concentra
Elanso [62]

Answer: Yes

Explanation:

Surface Concentration: In electrochemistry, there is an important distinction between the concentration of a species at the electrode’s surface and its concentration at some distance from the electrode’s surface (in what we call the bulk solution). Suppose we place an electrode in a solution of Fe3+ and fix the potential at 1.00 V. At this potential Fe3+ is stable—the standard state reduction potential for Fe3+ to Fe2+ is +0.771 V, the concentration of Fe3+ remains the same at all distances from the electrode’s surface.

Bulk Concentraton: If we change the electrode’s potential to +0.500 V, the concentration of Fe3+ at the electrode’s surface decreases to approximately zero. The concentration of Fe3+ increases as we move away from the electrode’s surface until it equals the concentration of Fe3+ in bulk solution. The resulting concentration gradient causes additional Fe3+ from the bulk solution to diffuse to the electrode’s surface.

5 0
3 years ago
How many kg moles of Sodium Sulphate will contain 10 kg of<br> Sodium?
enyata [817]

70.40mol cuz

1g sodium sulfate = 0.00704mol

take 10kg × 1000 = 10,000g

10,000g × 0.00704

final answer 70.40mol

(as per my thinking)

5 0
2 years ago
Read 2 more answers
I love touching the atmospheres crest
Lina20 [59]
That is super cool :))))
4 0
2 years ago
Other questions:
  • A thin‐walled tube with a diameter of 12 mm and length of 25 m is used to carry exhaust gas from a smoke stack to the laboratory
    10·1 answer
  • A decorative fountain was built so that water will rise to a hieght of 8 feet above the exit of the pipe. the pipe is 3/4 diamet
    5·1 answer
  • Write a statement that increases numPeople by 5. Ex: If numPeople is initially 10, the output is: There are 15 people.
    11·1 answer
  • Assume the triac of an AC discrete output module fails in the shorted state. How would this affect the device connected to this
    5·1 answer
  • A 40 mph wind is blowing past your house and speeds up as it flows up and over the roof. If the elevation effects are negligible
    14·1 answer
  • Air enters a counterflow heat exchanger operating at steady state at 27 C, 0.3 MPa and exits at 12 C. Refrigerant 134a enters at
    5·1 answer
  • Which of these parts of a cell phone is least likely to be found on the phone's circult board?
    5·1 answer
  • It is better to know or not to know?​
    6·2 answers
  • A person has driven a car 180 m in 40 seconds. What is the car’s speed?
    12·1 answer
  • What are the reasons why fine grained of alkali igneous rocks can not be used in cement
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!