A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies. A random sample of babies' weights (pounds) showed the following. $$\begin{array} { l l l l l l }
\text { Boys } & 8.0 & 4.7 & 7.3 & 6.2 & 3.4 \
\text { Girls } & 5.3 & 2.8 & 6.4 & 6.8 & 7.4
\end{array}$$ How many degrees of freedom would be used to test for a zero difference in means?
A)4
B)8
C)10
D)Must know ? to say.

Question

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies. A random sample of babies' weights (pounds) showed the following. $$\begin{array} { l l l l l l } 
\text { Boys } & 8.0 & 4.7 & 7.3 & 6.2 & 3.4 \
\text { Girls } & 5.3 & 2.8 & 6.4 & 6.8 & 7.4
\end{array}$$ How many degrees of freedom would be used to test for a zero difference in means?
A)4
B)8
C)10
D)Must know ? to say.

Quizplus · Accepted Answer

The degrees of freedom (df) for a two-sample t-test, assuming equal variances, is calculated as $df = n_1 + n_2 - 2$, where $n_1$ and $n_2$ are the sample sizes of the two groups. Here, $n_1 = 5$ (boys) and $n_2 = 5$ (girls), so $df = 5 + 5 - 2 = 8$.