Instruction 15-14
Recent Studies Have Found That Australian Children Are

Multiple Choice

Instruction 15-14
Recent studies have found that Australian children are more obese than in the past. The amount of time children spent watching television has received much of the blame. A survey of 100 ten-year-olds revealed the following with regards to weights and average number of hours a day spent watching television. You are interested in testing whether the average number of hours spent watching TV and weights are independent at 1% level of significance.
| TV Hours |
$$\begin{array} { | l | c | c | c | c | } \hline \text { Weights } & 0 - 3 & 3 - 6 & 6 + & \text { Total } \\\hline \text { More than 10 kg overweight } & 1 & 9 & 20 & 30 \\\hline \text { Within 10 kg of normal weight } & 20 & 15 & 15 & 50 \\\hline \text { More than 10 kg underweight } & 10 & 5 & 5 & 20 \\\hline \text { Total } & 31 & 29 & 40 & 100 \\\hline\end{array}$$
-Referring to Instruction 15-14,the degrees of freedom of the test statistic are

A) 9.
B) 1.
C) 4.
D) 2.