By taking covience sample

first 21 obs in P and next remaining 9 obs in S

input <- read.csv("C:/Users/localadmin/Downloads/input.csv")
View(input)
P<-head(input, 21)
s <- input[c(22:30),] 
cor(P)
##                                               Ticket.sales Stadium.Quality
## Ticket.sales                                     1.0000000       0.2419721
## Stadium.Quality                                  0.2419721       1.0000000
## Home_Team_Current.season.s.winning.percentage    0.5112595       0.1015776
## Away_Team_Current.season.s.winning.percentage    0.2121532      -0.2368883
## Distance.B.w.1.teams                             0.2747518       0.1715792
## Weekend                                          0.3639809      -0.1851993
## Free.to.air.Tv                                   0.3455727      -0.3052570
## X.of.promotions.provided                         0.9667682       0.1628325
##                                               Home_Team_Current.season.s.winning.percentage
## Ticket.sales                                                                     0.51125954
## Stadium.Quality                                                                  0.10157764
## Home_Team_Current.season.s.winning.percentage                                    1.00000000
## Away_Team_Current.season.s.winning.percentage                                    0.09114916
## Distance.B.w.1.teams                                                            -0.15762890
## Weekend                                                                         -0.22342133
## Free.to.air.Tv                                                                   0.02932318
## X.of.promotions.provided                                                         0.52848833
##                                               Away_Team_Current.season.s.winning.percentage
## Ticket.sales                                                                     0.21215319
## Stadium.Quality                                                                 -0.23688833
## Home_Team_Current.season.s.winning.percentage                                    0.09114916
## Away_Team_Current.season.s.winning.percentage                                    1.00000000
## Distance.B.w.1.teams                                                             0.26745150
## Weekend                                                                          0.19237116
## Free.to.air.Tv                                                                   0.01221097
## X.of.promotions.provided                                                         0.20772176
##                                               Distance.B.w.1.teams
## Ticket.sales                                             0.2747518
## Stadium.Quality                                          0.1715792
## Home_Team_Current.season.s.winning.percentage           -0.1576289
## Away_Team_Current.season.s.winning.percentage            0.2674515
## Distance.B.w.1.teams                                     1.0000000
## Weekend                                                  0.3206036
## Free.to.air.Tv                                           0.1833685
## X.of.promotions.provided                                 0.3506260
##                                                  Weekend Free.to.air.Tv
## Ticket.sales                                   0.3639809     0.34557268
## Stadium.Quality                               -0.1851993    -0.30525697
## Home_Team_Current.season.s.winning.percentage -0.2234213     0.02932318
## Away_Team_Current.season.s.winning.percentage  0.1923712     0.01221097
## Distance.B.w.1.teams                           0.3206036     0.18336846
## Weekend                                        1.0000000     0.45226702
## Free.to.air.Tv                                 0.4522670     1.00000000
## X.of.promotions.provided                       0.3929980     0.39169132
##                                               X.of.promotions.provided
## Ticket.sales                                                 0.9667682
## Stadium.Quality                                              0.1628325
## Home_Team_Current.season.s.winning.percentage                0.5284883
## Away_Team_Current.season.s.winning.percentage                0.2077218
## Distance.B.w.1.teams                                         0.3506260
## Weekend                                                      0.3929980
## Free.to.air.Tv                                               0.3916913
## X.of.promotions.provided                                     1.0000000
L<-lm(Ticket.sales~X.of.promotions.provided,data=P)
summary(L)
## 
## Call:
## lm(formula = Ticket.sales ~ X.of.promotions.provided, data = P)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -8609.4 -4208.7  -403.4  1848.1 19776.1 
## 
## Coefficients:
##                          Estimate Std. Error t value Pr(>|t|)    
## (Intercept)              7965.434   3675.534   2.167   0.0431 *  
## X.of.promotions.provided    2.241      0.136  16.483 1.04e-12 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 7334 on 19 degrees of freedom
## Multiple R-squared:  0.9346, Adjusted R-squared:  0.9312 
## F-statistic: 271.7 on 1 and 19 DF,  p-value: 1.036e-12
pre<-predict(L,newdata=s[,-1])
pre
##        22        23        24        25        26        27        28 
## 16534.237 14593.200 13806.475 11847.507 12652.163 11589.748 10316.643 
##        29        30 
##  9917.677 10525.092
s$Ticket.sales
## [1] 10061  9858  8686  7873  6969  5390  4769  3960  3807

By taking random sampling

myTrain <- input[sample(1:nrow(input), 0.7*nrow(input)),]

myTest<- input[-sample(1:nrow(input), 0.7*nrow(input)),]
cor(myTrain)
##                                               Ticket.sales Stadium.Quality
## Ticket.sales                                     1.0000000      0.43064982
## Stadium.Quality                                  0.4306498      1.00000000
## Home_Team_Current.season.s.winning.percentage    0.5272892      0.08432209
## Away_Team_Current.season.s.winning.percentage    0.6116149      0.12857940
## Distance.B.w.1.teams                             0.3444225      0.28338955
## Weekend                                          0.3591333      0.17960530
## Free.to.air.Tv                                   0.2510682      0.06110296
## X.of.promotions.provided                         0.9963348      0.44154066
##                                               Home_Team_Current.season.s.winning.percentage
## Ticket.sales                                                                     0.52728920
## Stadium.Quality                                                                  0.08432209
## Home_Team_Current.season.s.winning.percentage                                    1.00000000
## Away_Team_Current.season.s.winning.percentage                                    0.30996059
## Distance.B.w.1.teams                                                             0.24459803
## Weekend                                                                          0.06123724
## Free.to.air.Tv                                                                   0.05000000
## X.of.promotions.provided                                                         0.52308807
##                                               Away_Team_Current.season.s.winning.percentage
## Ticket.sales                                                                     0.61161486
## Stadium.Quality                                                                  0.12857940
## Home_Team_Current.season.s.winning.percentage                                    0.30996059
## Away_Team_Current.season.s.winning.percentage                                    1.00000000
## Distance.B.w.1.teams                                                             0.06228234
## Weekend                                                                         -0.16778901
## Free.to.air.Tv                                                                  -0.08219949
## X.of.promotions.provided                                                         0.59752582
##                                               Distance.B.w.1.teams
## Ticket.sales                                            0.34442245
## Stadium.Quality                                         0.28338955
## Home_Team_Current.season.s.winning.percentage           0.24459803
## Away_Team_Current.season.s.winning.percentage           0.06228234
## Distance.B.w.1.teams                                    1.00000000
## Weekend                                                 0.36610222
## Free.to.air.Tv                                          0.20362411
## X.of.promotions.provided                                0.35832172
##                                                   Weekend Free.to.air.Tv
## Ticket.sales                                   0.35913334     0.25106815
## Stadium.Quality                                0.17960530     0.06110296
## Home_Team_Current.season.s.winning.percentage  0.06123724     0.05000000
## Away_Team_Current.season.s.winning.percentage -0.16778901    -0.08219949
## Distance.B.w.1.teams                           0.36610222     0.20362411
## Weekend                                        1.00000000     0.61237244
## Free.to.air.Tv                                 0.61237244     1.00000000
## X.of.promotions.provided                       0.36659211     0.24330855
##                                               X.of.promotions.provided
## Ticket.sales                                                 0.9963348
## Stadium.Quality                                              0.4415407
## Home_Team_Current.season.s.winning.percentage                0.5230881
## Away_Team_Current.season.s.winning.percentage                0.5975258
## Distance.B.w.1.teams                                         0.3583217
## Weekend                                                      0.3665921
## Free.to.air.Tv                                               0.2433086
## X.of.promotions.provided                                     1.0000000
lin<- lm(Ticket.sales~X.of.promotions.provided,data=myTrain)

summary(lin)
## 
## Call:
## lm(formula = Ticket.sales ~ X.of.promotions.provided, data = myTrain)
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -7746.1  -342.7    43.6  1464.5  6854.5 
## 
## Coefficients:
##                           Estimate Std. Error t value Pr(>|t|)    
## (Intercept)              1.936e+03  1.044e+03   1.854   0.0793 .  
## X.of.promotions.provided 2.395e+00  4.717e-02  50.771   <2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 3121 on 19 degrees of freedom
## Multiple R-squared:  0.9927, Adjusted R-squared:  0.9923 
## F-statistic:  2578 on 1 and 19 DF,  p-value: < 2.2e-16
pred<-predict(lin,newdata = myTest[,-1])
pred
##         1         8        10        15        18        20        21 
## 90894.457 79418.084 81547.152 47053.370 36733.735 17952.909 15459.815 
##        26        29 
##  6943.541  4021.760
myTest$Ticket.sales
## [1] 97749 80883 73870 47097 36324 17600 14861  6969  3960