What does overfitting mean?

Load the nycflights13 package (library(nycflights13)) and use the flights dataset. I want to know if there is a difference in the average dep_delay between United (UA) and Delta (DL) on flights leaving JFK for LAX.    Here are the results of that test > t.test(dep_delay ~ carrier, df) data: dep_delay by carriert = -2.1714, df = 4171.9, p-value = 0.02995alternative hypothesis: true difference in means is not equal to 095 percent confidence interval:-3.7068150 -0.1892111sample estimates:mean in group DL mean in group UA 5.668539                           7.616552 What is the appropriate conclusion at the

Run the following code to fit the model predicting Happiness from Region and LifeExpectanncy. lm(Happiness ~ factor(Region)  + LifeExpectancy, HappyPlanetIndex) The coefficient of factor(Region)2 is 0.263.  What does this mean?  

e-grocers sell groceries over the internet.  Customers enter their orders, pay by credit card, and receive delivery by truck.  A potential e-grocer analyzed the market and determined that the average order would have to exceed $85 if the e-grocer were to be profitable.   What is the appropriate alternative hypothesis?

The assumptions for a linear regression model are met if which of the following are true (Select all that apply)

There are 52 cards in a standard deck of cards separated into 4 suits (hearts, diamonds, clubs, and spades) each with cards A, 2-10, J, Q, K. There are 2 decks next two each other (Deck 1 and Deck 2).  I select one card at random from Deck 1 and 1 card at random from Deck 2.  What is the probability both cards are hearts? Report your answer as a decimal to 4 decimal places

e-grocers sell groceries over the internet.  Customers enter their orders, pay by credit card, and receive delivery by truck.  A potential e-grocer analyzed the market and determined that the average order would have to exceed $85 if the e-grocer were to be profitable.  To determine whether an e-grocery would be profitable in one large city, she offered the service and recorded the size of the order for a random sample of 85 customers.   sample mean = $89.22 sample sd = $17.30 What is the t-test statistic? Report your answer to 3 decimal places.  

Using the nycflights13 data. I want to know if there is a difference in the average dep_delay between United (UA) and Delta (DL) on flights leaving JFK for LAX. What is the appropriate test?

Fred Flintstone is the latest hot commodity on the stock circuit.  He is picking profitable stocks at a fantastic rate.  A test was run (based on the last 30 stocks he picked) to see if the average return on his stocks significantly exceeded 0. 

A group of 25 husbands and wives were chosen randomly.  Each person was asked to indicate the most he/she would be willing to pay for a new car (assuming a new car was going to be purchased).  The researcher would like to test the hypothesis that husbands are willing spend more than their wives on average at the 5% significance level. This is an example of what type of test?