Please download the answer file and edit it on RStudio. Write your student number in the correct place at the beginning of the answer file. When you finish, send the answers.R file to the answers’ mailbox. All questions are independent and can be answered in any order.

  1. Download the file rubber.txt, store it in your computer, and read it into a data frame called rubber. Show summary(rubber).
##        id        rep          N               x1              x2       
##  Min.   :1.000   a:54   Min.   :1.000   Min.   : 10.0   Min.   : 15.7  
##  1st Qu.:2.000   b:55   1st Qu.:1.000   1st Qu.: 70.0   1st Qu.:194.0  
##  Median :3.000   c:51   Median :2.000   Median :200.0   Median :290.0  
##  Mean   :2.994   d: 9   Mean   :1.529   Mean   :189.3   Mean   :283.5  
##  3rd Qu.:4.000   s: 1   3rd Qu.:2.000   3rd Qu.:250.0   3rd Qu.:377.5  
##  Max.   :7.000          Max.   :2.000   Max.   :434.0   Max.   :502.0  
##                                                                        
##        y1              y2            src    
##  Min.   : 12.9   Min.   : 11.3   185a34:40  
##  1st Qu.:207.0   1st Qu.:280.0   1e4a6e:14  
##  Median :309.5   Median :400.0   3b2b4b:15  
##  Mean   :315.2   Mean   :402.4   6ed952:30  
##  3rd Qu.:409.5   3rd Qu.:515.0   7183bd:30  
##  Max.   :775.0   Max.   :775.0   andres:30  
##                                  e3459b:11
# write here
  1. Show all the different values of rubber$src and the number of times each one appears. Show this table in a nice way, using the kable command. There may be some warnings, but they are not important.
Var1 Freq
185a34 40
1e4a6e 14
3b2b4b 15
6ed952 30
7183bd 30
andres 30
e3459b 11 
# write here
  1. Modify the data frame rubber. Create a new column called dx with the values x2-x1. Create a new column called dy, with the values y2-y1. Create a new column called clip, with the values y1-x2. Show summary(rubber)
# write here
##        id        rep          N               x1              x2       
##  Min.   :1.000   a:54   Min.   :1.000   Min.   : 10.0   Min.   : 15.7  
##  1st Qu.:2.000   b:55   1st Qu.:1.000   1st Qu.: 70.0   1st Qu.:194.0  
##  Median :3.000   c:51   Median :2.000   Median :200.0   Median :290.0  
##  Mean   :2.994   d: 9   Mean   :1.529   Mean   :189.3   Mean   :283.5  
##  3rd Qu.:4.000   s: 1   3rd Qu.:2.000   3rd Qu.:250.0   3rd Qu.:377.5  
##  Max.   :7.000          Max.   :2.000   Max.   :434.0   Max.   :502.0  
##                                                                        
##        y1              y2            src           dx               dy         
##  Min.   : 12.9   Min.   : 11.3   185a34:40   Min.   :-47.90   Min.   :-105.00  
##  1st Qu.:207.0   1st Qu.:280.0   1e4a6e:14   1st Qu.: 85.00   1st Qu.:  80.00  
##  Median :309.5   Median :400.0   3b2b4b:15   Median :106.00   Median :  95.00  
##  Mean   :315.2   Mean   :402.4   6ed952:30   Mean   : 94.18   Mean   :  87.21  
##  3rd Qu.:409.5   3rd Qu.:515.0   7183bd:30   3rd Qu.:130.25   3rd Qu.: 120.75  
##  Max.   :775.0   Max.   :775.0   andres:30   Max.   :233.00   Max.   : 200.00  
##                                  e3459b:11                                     
##       clip       
##  Min.   :-70.00  
##  1st Qu.: 17.00  
##  Median : 19.00  
##  Mean   : 31.75  
##  3rd Qu.: 20.00  
##  Max.   :435.00  
##
  1. Draw this
# write here

  1. Create a new data frame, called clean_rubber containing a subset of rubber, where clip>0 and clip<50. Plot the histogram of clean_rubber$clip
# write here

  1. Plot two figures at the same time, only for the subset where src=="andres" when N==1 and when N==2. Color should correspond to id
# write here

  1. Plot only the subset where src=="185a34" and N==2. Build a linear model for these points and store it on the variable model. Draw the line described by the model.
# write here

  1. Show the coefficients of the model
# write here
## (Intercept)          dx 
##  45.6654794   0.4011217
  1. In your own words, what is the meaning of these coefficients
# write here