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Consider the scores of a random sample of 16 teacher education students at certain university on ethical standard are as follows: 84,79,90,100,105,83,87,112,95,76,84,89,101,88,90 and 105. Test at the 0.05 level significance, the median score for the population is less than 90
A certain experiment consisted of l= 5 treatments, with sample sizes n1=n2=n3=n4=n5=4. The sun of squares was SSTr=43.7 and SSE=79.8.
a. How many degrees of freedom are there for SSTr?
b. How many degrees of freedom are there for SSE?
c. Find the treatment mean square MSTr.
d. Find the error mean square MSE.
e. Find the value of the test statistic for testing the hypothesis
f. Find the level a=0.05 critical value
g. State your conclusion regarding null hypothesis. Use the a=0.05 level of significance.
If only one city were tested,and the true mean for this city was equal to the national average of 487,what is the probability that null hypothesis would be rejected, leading to a true conclusion
Independent random samples were drawn from approximately normal populations. The sample means x1= 6.8 and x2= 4.9. the sample standard deviations were s1= 1.6 and s2= 1.3. the sample sizes were n1= 12 and n2= 10
a) find the value of the test statistic t.
b) find the number of degrees of freedom for t.
c) make an interpretation of the result. Do you reject null hypothesis at a= 0.01 level?
A vapor-compression refrigeration machine uses refrigerant-134a as much as 2 kg/min with operating conditions leaving the evaporator at a temperature of -14°C and a condenser pressure of 0.8 Mpa. Determine the COP value and cooling load of the machine.
A 3-phase, 50 Hz, 4-pole, 400 V, wound rotor induction motor has a Δ-connected stator winding and Y-connected rotor winding. There are 80% as many rotor conductors as stator conductors. For speed of 1425 rpm, calculate the rotor induced emf between the two slip rings.
A cell reaction is given by , A+B ----- A+B. Calculate the E° cell and number of electrons n involved in cell reaction. Given that concentration ratio of [A] to [B] is 0.1 and cell shows an emf of 1.13006 v at 30°C and 1.13105 v at 40°C.
If want to design a machine, the general demands are followings except ( ). A.Realize the required functions B.Good performance C.High cost D.High efficiency
The machine consists of the followings except ( ).
A.Prime mover B.Working system C.Transmission system D.Execution system
A spur standard gear mechanism, increase its module and remain its diameter unchanged, which
can( ).
A.Increase its load B.Increase its pressure angle C.Increase its transmission angle D.Increase its efficiency
