Records show that the average commute time for a person living in Atlanta in 2000 was 42 minutes. An analyst claims that the average commute time in 2007 was longer. The analyst takes a simple random sample of thirteen commuters in 2007 and calculates an average of 46.4 and a standard deviation of 3.8. (It is reasonable to assume that the population of commute times has a normal distribution.)

Which of the following is the appropriate test statistic?

t = (46.4 - 42.0)/(3.8/√13)

z = (42.0 - 46.4)/(3.8/√13)

z = (46.4 - 42.0)/(3.8/√13)

t = (42.0 - 46.4)/(3.8/√13)

None of the above

Option a)  t = (46.4 - 42.0)/(3.8/√13)

Step-by-step explanation:

Here we are given that Records show that the average commute time for a person living in Atlanta in 2000 was 42 minutes i.e. = 42

And to test this a sample of thirteen commuters in 2007 has been taken and calculates an average of 46.4 and a standard deviation of 3.8 i.e.;

Sample Mean, X bar = 46.4             Sample standard deviation,s = 3.8

Sample size, n = 13

Since, here we know nothing about population standard deviation so we will use t statistics here ;

  Test statistics =   ~

Therefore, appropriate test statistic = ~ .

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204