\authorandnumber{Carlos Rodriguez}
\problemdate{Wed Sep 02 2009 16:54:28 GMT-0400 (Eastern Daylight Time)}
\textbook{Statistics by Freedman, Pisani and Purves}
\partname{Reading Histograms}
\chaptername{Histograms}
\begin{problem}
\score{1}
Cut and paste the following code into R.


\begin{verbatim}
barplot(c(1,4,3,0.5),c(20,20,30,30),space=0,
  col=c("white","gray","white","white"),
  main="Histogram of Exam Scores", xlab="Score Points")
axis(1)
\end{verbatim}


Look at the generated picture.
Suppose that the gray bar is actually missing (we don't know its height)
but we are told that the fat block next to it represents 50\% of the
entries in the list. How tall is the missing block?

\begin{choice}
\gooditem{2.75}
\baditem{2.5}
\baditem{1.25}
\baditem{3}
\baditem{3.25}
\end{choice}


\begin{longanswer}
You may want to again Cut and Paste the following into R.


\begin{verbatim}
# ANSWERS:
# 2) Now the area of 9 corresponds to 50%. Thus the other correspond to,
pa = c(2,9,1.5)*50/9
# The missing block must contain whats missing from 100% about 31%
per = 100 - sum(pa)
# this should be about 14% so 2h/14 = 9/50 so,
Ans2 = (9/50)*per/2

# which is 2.75

\end{verbatim}
\end{longanswer}
\end{problem}
