Exercise #$1$ a$$

A professor will assign grades to their class as follows: any score more than $15$ points above average will receive an A $,$ from $0-15$ points $($inclusive$)$ above

average will receive a $B,$ from $0-15$ points below average will receive a $C,$ and more than $15$ points below average will receive a $D.$

Write a MATLAB function called grades.m which will take a single input, which is in an array of grades, and return $4$ outputs. The first output is the

number of A$\text{'}$s in the class, the second is the number of B$\text{'}$s$,$ the third is the number of C$\text{'}$s$,$ and the fourth is the number of D$\text{'}$s$.$ As a check, the MATLAB

commands $t=1$:$140$; $[$A$,$ B$,$ C$,$ D$]=$grades $(75+25*cos(t).*sin(3*t)$ should give $20A^{\text{'}}s,57B^{\text{'}}s,38$ C$\text{'}$s$,$ and $25$ D$\text{'}$s$.($Hopefully the grade

distribution at the end of this course will be somewhat better!$)$

Hints: Remember that the MATLAB mean command will calculate the average of an array of numbers. You will need a loop with a nested conditional to

do the counting. NOTE you need to combine a "for" loop and a conditional.