Please show all work in excel. Thank you!! MPG Horsepower Weight Age US Brand (1

Question

Please show all work in excel. Thank you!!

MPG Horsepower Weight Age US Brand (1=yes) 43.1 48 1985 1 0 19.9 110 3365 7 1 19.2 105 3535 8 1 17.7 165 3445 10 1 18.1 139 3205 5 1 20.3 103 2830 4 1 21.5 115 3245 8 0 16.9 155 4360 10 1 15.5 142 4054 7 1 18.5 150 3940 5 1 27.2 71 3190 3 1 41.5 76 2144 1 0 46.6 65 2110 0 0 23.7 100 2420 4 1 27.2 84 2490 6 1 39.1 58 1755 3 0 28.0 88 2605 4 1 24.0 92 2865 3 0 20.2 139 3570 2 0 20.5 95 3155 7 1 28.0 90 2678 5 1 34.7 63 2215 4 0 36.1 66 1800 7 0 35.7 80 1915 1 1 20.2 85 2965 7 1 23.9 90 3420 8 1 29.9 65 2380 3 1 30.4 67 3250 2 0 36.0 74 1980 1 0 22.6 110 2800 6 1 36.4 67 2950 2 1 27.5 95 2560 3 0 33.7 75 2210 1 0 44.6 67 1850 0 0 32.9 100 2615 3 1 38.0 67 1965 1 0 24.2 120 2930 3 0 38.1 60 1968 1 0 39.4 70 2070 0 0 25.4 116 2900 4 1 31.3 75 2542 2 1 34.1 68 1985 1 0 34.0 88 2395 2 0 31.0 82 2720 2 0 27.4 80 2670 5 1 22.3 88 2890 1 1 28.0 79 2625 4 1 17.6 85 3465 7 1 34.4 65 3465 2 0 20.6 105 3380 9 1 2. Consider the data in MPG. White house spokesman Sean Spicy (G) claims that the average age of vehicles in the US is at most 3.5 years and therefore regulations concerning older cars are not necessary. You work for the EPA (environmental protection agency) and you doubt this claim. You collect a sample (as displayed in the file MPG). At an alpha of .05, what is your conclusion? Please provide all the excel formulas you are using as well as intermediated calculations from the MPG file. In addition provide a 90% confidence interval, including a conclusion sentence.

Explanation / Answer

Ho: Average<=3.5

Ha: Average>3.5

Mean of age= 3.9 (excel formula- average(age))

to calculate t value, use t.dist(3.9-3.5,50-1,false)=0.366

to calculate critical t value, use t.inv(5%,50-1)=-1.677

calculated t value> critical t value implies we reject the null hypothesis. Average age of cars is not <=3.5years. Hence it is a false claim that average age of cars in US is atmost 3.5years and regulations related to older cars is not necessary.

to calculate standar deviation of sample, stdev.s(age)=2.765

to calculate confidence interval at 90%, use confidence.t(10%, 2.765,50)=0.655

So the confidence interval at 90% is 3.5+/-0.655 ie average age of cars lies between 2.844years to 4.155years

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