Part 2.1

hist(precip, col="grey",xlab="Inches", ylab="Number of Cities",breaks=50)

The help page says that if you want an exact number of breaks you need a vector giving the breakpoints between histogram cells.

Part 2.2

hist(precip, col=“grey” xlab=“Inches”, ylab=“Number of Cities”,breaks=50)

generated the error message: Error: unexpected symbol in “hist(precip, col=”grey" xlab"

The error message means that the symbol x after “grey” doesn’t make sense.

part 2.3

1:6+1:2
## [1] 2 4 4 6 6 8

[1] 2 4 4 6 6 8

we add the vectors 1 2 3 4 5 6 to 1 2 1 2 1 2 by the recycling rule.

1:7 + 1:2
## Warning in 1:7 + 1:2: longer object length is not a multiple of shorter
## object length
## [1] 2 4 4 6 6 8 8

[1] 2 4 4 6 6 8 8

we add the vectors 1 2 3 4 5 6 7 to 1 2 1 2 1 2 1 by the recycling rule.

part 3

url<-"http://www.stat.berkeley.edu/users/cgk/teaching/assets/flow-occ-table.txt"
traffic<- read.csv(file=url,header=TRUE)
head(traffic)
##     Occ1 Flow1   Occ2 Flow2   Occ3 Flow3
## 1 0.0100    14 0.0186    27 0.0137    17
## 2 0.0133    18 0.0250    39 0.0187    25
## 3 0.0088    12 0.0180    30 0.0095    11
## 4 0.0115    16 0.0203    33 0.0217    19
## 5 0.0069     8 0.0178    25 0.0123    13
## 6 0.0077    11 0.0151    24 0.0092    13
flow1<- traffic$Flow1
flow2<- traffic$Flow2
flow3<- traffic$Flow3

part 3.1

summary(flow1)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    0.00   17.00   67.00   65.82  101.00  203.00
summary(flow2)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##     4.0    35.0    84.0    74.8   107.0   174.0
summary(flow3)
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##     3.0    22.0    50.0    48.1    67.0   142.0

We use the mean of the flow to determine overall flow. The second lance has the highest mean flow and the third lane has the lowest mean flow.

part 3.2

hist(flow1,breaks=seq(from=0,to=225,by=25))

hist(flow2, breaks=seq(from=0,to=225,by=25))

hist(flow3, breaks=seq(from=0,to=225,by=25))