statistics
posted by G. .
In Dallas some fire trucks were painted yellow (not red) to heighten their visability. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow trucks made 135,035 runs and had 4 accidents. At a= .01, did the yellow fire trucks have a significantly lower accident rate? (a) state the hypothesis (b) state the decision rule and sketch it (c) find the proportions and z test statistic (d) make a decision (e) find the pvalue and interpret it (f) if statistically significant, do you think the difference is large enough to be important? If so, to whom, and why? (g)is the normally assumption fulfilled? Explain
Accident rate for Dallas Fire Trucks
Statistic Red Trucks Yellow Trucks
# of Accidentsx1=20accidents x2=4accid
# of fire runsn1=153,348 n2=135,035

Hypotheses:
Ho: pY = pR (R = red trucks; Y = yellow trucks)
Ha: pY < pR
You can use a binomial proportion 2sample ztest for this kind of problem.
Here is one formula for this type of test:
z = (pY  pR)/√(pq(1/n1 + 1/n2)
p = (x1 + x2)/(n1 + n2)
q = 1  p
pY = 4/135035
pR = 20/153348
p = (4 + 20)/(135035 + 153348)
q = 1  p
Convert to decimals and substitute into the formula. Calculate z. Compare to the cutoff z at .01 for a onetailed test (Ha shows a specific direction, so the test is onetailed). Determine the pvalue, which is the actual level of the test statistic. Determine whether to reject Ho (the null hypothesis) or fail to reject Ho. If you reject Ho, then you accept Ha and the test is statistically significant.
I hope this will help get you started.
Respond to this Question
Similar Questions

hard math
The jelly Junior school color is made by mixing red paint and yellow paint. The ratio of red to yellow is 3 to 5. How much red paint should be mixed with 20 oz of yellow? 
business
Here is a question on free trade. Country X and Country Z have a free trade agreement. If Country X buys trucks from Country Y and sells the trucks to a car dealer in Country Z, does the buyer need to pay duty on trucks. Why or why … 
Math
Mario replaced 72 tires on the small and large trucks in his fleet. He replaced 3 times as many tires on the large trucks as on the small. How many tires did he replaced on the small trucks? 
Geometry
A spherical storage tank has a diameter of 48 ft and is full of water. How many delivery trucks with cylindrical tanks measuring 8 ft in diameter and 10 ft long can be completely filled from the storage tank? 
university phoenix
In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow fire trucks made 135,035 … 
math
The CEO of a transportation company wants to use a large amount of cash for the purchase of additional new trucks and trailers rather than paying bonuses to its employees. The new trucks are more productive than the existing trucks … 
econ
Consider the market for trucks. Assume that the demand for trucks is given by 60 2 5 D Q P Y where P is price per truck and Y is the income of the buyers. The supply of trucks is given by 30 5 3 S Q P W where W is the price of all … 
Math
An explosion has occurred in Canada. Its blast radius was a regular circle that can be modelled by the equation x2 +y2=100, where x and y are measured in km. The blast destroyed everything within the circle. a) Canada has 4 fire stations … 
Math
There were 12 new trucks brought to the sales lot on Monday. Three of them were red. At this rate if 40 trucks are brought to the lot by Thursday, how many of them will be Red? 
math
a company owns only cars and trucks. The sum of the cars and trucks owned by the company is 60. One sixh of the red and one half of the trucks are red. If there are twice as many red trucks as red cars, how many cars are not red?