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t-test of MPG by Transmission

## 
##  Pearson's product-moment correlation
## 
## data:  cars1$mpg and cars1$am
## t = 4.1061, df = 30, p-value = 0.000285
## alternative hypothesis: true correlation is not equal to 0
## 95 percent confidence interval:
##  0.3175583 0.7844520
## sample estimates:
##       cor 
## 0.5998324

## 
##  Welch Two Sample t-test
## 
## data:  cars1$mpg by cars1$am_char
## t = -3.7671, df = 18.332, p-value = 0.001374
## alternative hypothesis: true difference in means between group Automatic and group Manual is not equal to 0
## 95 percent confidence interval:
##  -11.280194  -3.209684
## sample estimates:
## mean in group Automatic    mean in group Manual 
##                17.14737                24.39231

Conclusion: Manual cars get more MPG than automatic ones