A biology professor claims that, on the average, 10% of her students get a grade of A, 30% get a B, 35% get a C, 10% get a D, and 15% get an F. The grades of a random sample of 113 students were Recorded. The following table presents the results.

$\begin{array} { c | l l l l l }
\text { Grade } & 1 & 2 & 3 & 4 & 5 \
\hline \text { Observed } & 3 & 34 & 38 & 12 & 26
\end{array}$

Compute the expected frequencies.
A) 3,34,38,12,26
B) 0.027,0.301,0.336,0.106,0.23
C) 11.3,33.9,39.55,11.3,16.95
D) 22.6,22.6,22.6,22.6,22.6

Question

A biology professor claims that, on the average, 10% of her students get a grade of A, 30% get a B, 35% get a C, 10% get a D, and 15% get an F. The grades of a random sample of 113 students were Recorded. The following table presents the results.

$\begin{array} { c | l l l l l } 
\text { Grade } & 1 & 2 & 3 & 4 & 5 \
\hline \text { Observed } & 3 & 34 & 38 & 12 & 26
\end{array}$

Compute the expected frequencies.
A) 3,34,38,12,26
B) 0.027,0.301,0.336,0.106,0.23
C) 11.3,33.9,39.55,11.3,16.95
D) 22.6,22.6,22.6,22.6,22.6

Quizplus · Accepted Answer

The expected frequency for each grade can be found by multiplying the total sample size (n=113) by the percentage of students expected to receive each grade.

Expected frequency for A = 0.10 x 113 = 11.3
Expected frequency for B = 0.30 x 113 = 33.9
Expected frequency for C = 0.35 x 113 = 39.55
Expected frequency for D = 0.10 x 113 = 11.3
Expected frequency for F = 0.15 x 113 = 16.95

Therefore, the best choice is C.

A Biology Professor Claims That, on the Average, 10% of Her