Problem PQ$4.$ Modifying and Filling In Python Code.

$($a$)[6$ points$]$ Here are the formulas for computing the mean, $,$ and standard deviation, $,$ of a

set of $n$ values:

$=\frac{{\displaystyle \underset{i=1}{\overset{n}{}}}{x}_i}{n}=\frac{x_1+x_2+\text{c}\text{d}\text{o}\text{t}\text{s}+x_n}{n},=\sqrt[\phantom{2}]{\frac{{\displaystyle \underset{i=1}{\overset{n}{}}}(x_i-{)}^2}{n}}=\sqrt[\phantom{2}]{\frac{{\displaystyle \underset{i=1}{\overset{n}{}}}{x}_i^2}{n}-{}^2}$

The following Python functions returns the mean of the values of a passed list, x$,$ using the

formula for the mean, $,$ given above.

def mean$($x$)$:

xsum $=0$

for i in range$($len$($x$))$:

xsum $+=$ x$[$i$]$

return xsum$/$len$($x$)$

Write another Python function $($which could call the function above$)$ to return the standard

deviation of the values of a passed list, x$.$ Also $($for purposes of assigning partial credit$),$

circle the formula for the standard deviation, $\backslash$sigma $,$ that you used above.

b$)[6$ points$]$ The text file autompg.dat contains $398$ lines of automobile mileage data of the

following, tab$-$separated data $($where the character $|$ is used only to denote the tab locations$)$:

car name $|$ model year $|$ number of cylinders $|$ miles per gallon

For example, the first two lines of the file might look like:

Prius $2005455\mathrm{.}0$

Escalade $2005816\mathrm{.}5$

Add Python expressions$/$statements to complete the program below, which should read the

data from the file and display it to the screen. Assume car name contains no spaces.

# Open the file

input $=$ file.open$()$

# name is of type str

# year and cyls are of type int

# mpg is of type float

print$("$Name $\backslash$t Year $\backslash$t # Cyls$.\backslash$t MPG$")$

# Get input from file

for :

# within for loop body, display that line of data

print$($f$"\{$name$\}\backslash$t $\{$year$\}\backslash$t $\{$cyls$\}\backslash$t $\{$mpg$\}")$

# end for loop body

# Close the file

input.close$()$

$($c$)[8$ points

Assume that values is a $101-$element list containing measurements from a scientific

experiment, as declared in the Python code below.

Add Python statements that would complete the program below to count the number of

positive values, negative values, and zero values in the list, and $($complete the code to$)$

write out a message summarizing how many values of each type were found.

values $=[0$ for i in range$(101)]$ # LIST DECLARATION

# OTHER CODE TO INITIALIZE values WOULD BE HERE $($DO NOT WRITE$)$

# DECLARE$/$INITIALIZE YOUR OTHER VARIABLES HERE

for i in :

# end for loop body

# Print statements: COMPLETE AS NECESSARY

print$($f$"$# of positive entries: $")$

print$($f$"$# of negative entries: $")$

print$($f$"$# of zero entries: $")$