A Biology Professor Claims That, on the Average, 20% of Her

question 2

Short Answer

A biology professor claims that, on the average, 20% of her students get a grade of A, 30% get a B, 35% get a C, 10% get a D, and 5% get an F. The grades of a random sample of 137 students were recorded. The following table presents the results.
$\begin{array} { c | l l l l l } \text { Grade } & 1 & 2 & 3 & 4 & 5 \\\hline \text { Observed } & 27 & 37 & 52 & 16 & 5\end{array}$
i). Compute the expected frequencies.
ii). What is the value of $\chi ^ { 2 }$ ?
iii). How many degrees of freedom are there?
iv). Test the hypothesis that the grades follow the distribution claimed by the professor. Use the $\alpha$ = 0.05 level of significance.

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Definitions:

Translational Control

The regulation of protein synthesis in a cell by various mechanisms that act on the process of translating RNA into protein.

Transcriptional Control

The regulation of gene expression at the transcription stage, determining when and how much RNA is produced from a gene.

Repressible System

A regulatory system in which the presence of a specific molecule inhibits gene expression.

Prader-Willi Syndrome

A rare genetic disorder characterized by a variety of symptoms including reduced muscle tone, feeding difficulties in infancy, overeating in later childhood, and intellectual impairment.