Exercise 2 Page 692

We want to find relative frequencies by row. To do so, we will start by completing the given table.

	TV	Internet	Total
7th grade	$13;$	$49;$
8th grade	$20;$	$68;$
Total

Let's find the sums of each row and column. Let's write the newly obtained information in our table.

	TV	Internet	Total
7th grade	$13;$	$49;$	$62$
8th grade	$20;$	$68;$	$88$
Total	$33$	$117$

We have two ways of calculating the grand total. We can add the number of $7\text{th grade students}$ to the number of $8\text{th grade students},$ or we can add the students who get news from $\text{TV}$ to the students who get news from the $\text{internet}.$ These two numbers must be the same! Now, we can complete our table!

	TV	Internet	Total
7th grade	$13;$	$49;$	$62$
8th grade	$20;$	$68;$	$88$
Total	$33$	$117$	$150$

To find the relative frequencies by row, we calculate the ratios of each value and the total in that row. We will round the results to the nearest hundredth.

	TV	Internet	Total
7th grade	$13;$ $\frac{13}{62}\approx 0.21$	$49;$ $\frac{49}{62}\approx 0.79$	$62;$ $\frac{62}{62}=1.00$
8th grade	$20;$ $\frac{20}{88}\approx 0.23$	$68;$ $\frac{68}{88}\approx 0.77$	$88;$ $\frac{88}{88}=1.00$
Total	$33$	$117$	$150$

Looking at the relative frequencies, we can say that many more $7^{\text{th}}$ and $8^{th}$ grade students are getting their news from the internet rather than from TV.