prediction of delivery time using sorting time

deltime=read.csv("E:\\Data science\\delivery_time.csv")
View(deltime)
summary(deltime)
##        Dt              St       
##  Min.   : 8.00   Min.   : 2.00  
##  1st Qu.:13.50   1st Qu.: 4.00  
##  Median :17.83   Median : 6.00  
##  Mean   :16.79   Mean   : 6.19  
##  3rd Qu.:19.75   3rd Qu.: 8.00  
##  Max.   :29.00   Max.   :10.00
attach(deltime)
qqnorm(Dt)

cor(St,Dt)
## [1] 0.8259973
plot(St,Dt)

windows()
m1<-lm("Dt~St",data=deltime)
m1
## 
## Call:
## lm(formula = "Dt~St", data = deltime)
## 
## Coefficients:
## (Intercept)           St  
##       6.583        1.649
pv<-predict(m1,deltime)
pv
##         1         2         3         4         5         6         7 
## 23.072933 13.178814 16.476853 21.423913 23.072933 16.476853 18.125873 
##         8         9        10        11        12        13        14 
## 11.529794 23.072933 21.423913 19.774893 13.178814 18.125873 11.529794 
##        15        16        17        18        19        20        21 
## 11.529794 13.178814 16.476853 18.125873  9.880774 18.125873 14.827833
pread<-as.data.frame(pv)
pread
##           pv
## 1  23.072933
## 2  13.178814
## 3  16.476853
## 4  21.423913
## 5  23.072933
## 6  16.476853
## 7  18.125873
## 8  11.529794
## 9  23.072933
## 10 21.423913
## 11 19.774893
## 12 13.178814
## 13 18.125873
## 14 11.529794
## 15 11.529794
## 16 13.178814
## 17 16.476853
## 18 18.125873
## 19  9.880774
## 20 18.125873
## 21 14.827833
final<-cbind(deltime,pv)
final
##       Dt St        pv
## 1  21.00 10 23.072933
## 2  13.50  4 13.178814
## 3  19.75  6 16.476853
## 4  24.00  9 21.423913
## 5  29.00 10 23.072933
## 6  15.35  6 16.476853
## 7  19.00  7 18.125873
## 8   9.50  3 11.529794
## 9  17.90 10 23.072933
## 10 18.75  9 21.423913
## 11 19.83  8 19.774893
## 12 10.75  4 13.178814
## 13 16.68  7 18.125873
## 14 11.50  3 11.529794
## 15 12.03  3 11.529794
## 16 14.88  4 13.178814
## 17 13.75  6 16.476853
## 18 18.11  7 18.125873
## 19  8.00  2  9.880774
## 20 17.83  7 18.125873
## 21 21.50  5 14.827833