model, mpg, cyl,disp,hp, drat, wt,qsec,vs,am, gear, carb Mazda RX4,21,6,160,110,

Question

model, mpg, cyl,disp,hp, drat, wt,qsec,vs,am, gear, carb Mazda RX4,21,6,160,110,3.9,2.62,16.46,0,1,4,4 Mazda RX4 Wag, 21,6,160,110,3.9,2.875,17.02,0,1,4,4 Datsun 710,22.8,4,108,93,3.85, 2.32,18.61,1,1,4,1 Hornet 4 Drive, 21.4,6, 258,110,3.08,3.215,19.44,1,0, 3,1 Hornet Sportabout,18.7,8,360,175,3.15,3.44,17.02,0,0,3,2 Valiant,18.1, 6,225,105, 2.76, 3.46,20.22,1,0,3,1 Duster 360,14.3,8,360,245,3.21,3.57,15.84,0,0,3,4 Merc 240D, 24.4,4, 146.7,62, 3.69,3.19,20,1,0,4,2 Merc 230,22.8,4,140.8,95, 3.92,3.15,22.9,1,0,4,2 Merc 280,19.2,6,167.6,123, 3.92,3.44,18.3,1,0,4,4 Merc 280C,17.8,6, 167.6,123, 3.92, 3.44,18.9,1,0,4, 4 Merc 450SE, 16.4,8,275.8,180,3.07,4.07,17.4,0,0,3,3 Merc 450SL, 17.3,8,275.8,180,3.07,3.73,17.6,0,0,3,3 Merc 450SLC, 15.2,8,275.8,180,3.07,3.78,18,0,0,3, 3 Cadillac Fleetwood,10.4,8, 472,205,2.93,5.25,17.98,0,0, 3, 4 Lincoln Continental, 10.4,8,460,215,3, 5.424,17.82,0,0,3,4 Chrysler Imperial, 14.7, 8,440,230,3·23,5·345,17.42,0,0, 3,4 Fiat 128, 32.4,4,78.7,66, 4.08,2.2,19.47,1,1,4,1 Honda Civic, 30.4, 4,75.7,52,4.93, 1.615,18.52,1,1, 4,2 Toyota Corolla, 33.9, 4,71.1,65, 4.22,1.835,19.9,1,1,4,1 Toyota Corona,21.5,4,120.1,97,3.7,2.465, 20.01,1,0,3,1 Dodge Challenger, 15.5, 8, 318, 150, 2·76, 3.52, 16.87, 0, 0, 3, 2 AMC Javelin, 15.2,8, 304,150,3.15, 3.435,17.3,0,0,3,2 Camaro Z28,13.3,8,350,245, 3.73,3.84,15.41,0,0,3, 4 Pontiac Firebird,19.2,8,400,175, 3.08,3.845,17.05,0,0,3,2 Fiat X1-9,27.3, 4, 79, 66,4.08,1.935,18.9,1,1,4,1 Porsche 914-2,26, 4,120.3,91,4.43,2.14,16.7,0,1,5, 2 Lotus Europa, 30.4,4,95.1,113,3.77,1.513,16.9,1,1,5,2 Ford Pantera L,15.8, 8,351,264,4.22,3.17,14.5,0,1,5, 4 Ferrari Dino,19.7,6, 145, 175, 3.62,2.77,15.5,0,1,5,6 Maserati Bora,15, 8,301,335, 3.54, 3.57,14.6,0,1,5,8 Volvo 142E,21·4,4,121,109,4.11,2·78,18·6,1,1,4,2

Explanation / Answer

R codes :

library(ggplot2)
attach(mtcars)
t.test(mpg,mu=25,alt="less") #To test H0 : mu = 25 ag. H1 : mu < 25

One Sample t-test

data: mpg
t = -4.6079, df = 31, p-value = 3.293e-05
alternative hypothesis: true mean is less than 25
95 percent confidence interval:
-Inf 21.89707
sample estimates:
mean of x
20.09062

Since p-value is very small, we reject H0 and conclude that the average fuel mileage is significantly less than 25 miles per gallon.
The confidence interval : (- Inf, 21.89707)

success=length(which(am==1)) #Cars having manual transmission are considered to be a success
prop.test(success,length(am),p=0.6) #To test H0 : p = 0.6 ag. H1 : not H0

1-sample proportions test with continuity correction

data: success out of length(am), null probability 0.6
X-squared = 4.2305, df = 1, p-value = 0.0397
alternative hypothesis: true p is not equal to 0.6
95 percent confidence interval:
0.2421914 0.5921457
sample estimates:
p
0.40625

Since p-value < 0.05, we reject H0 at 5% level and conclude that the proportion of cars having manual transmission were significantly not equal to 60%

Confidence interval : ( 0.2421914, 0.5921457)

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.