of 320 consumers polled, some purchase Blu-ray movies, some purchase movies on DVD, and some do both. If 300 people polled purchase Blu-ray discs and 280 purchase DVD's and Blu-ray discs, how many people only buy DVD's?
To find the number of people who only buy DVDs, we need to subtract the number of people who purchase both Blu-ray discs and DVDs, as well as the number of people who purchase only Blu-ray discs, from the total number of people who purchase DVDs.
First, let's determine the number of people who purchase both Blu-ray discs and DVDs. We know that there are 320 consumers polled, and among them, 280 people purchase both Blu-ray discs and DVDs. Therefore, 280 people fall into this category.
Next, we need to calculate the number of people who purchase only Blu-ray discs. We know that 300 people polled purchase Blu-ray discs, and some of them also purchase DVDs. To determine how many purchase only Blu-ray discs, we subtract the number of people who purchase both from the total number of people who purchase Blu-ray discs. Thus, 300 - 280 = 20 people purchase only Blu-ray discs.
Now, let's find the number of people who only buy DVDs. We know that 320 consumers were polled, and we already determined that there are 280 people who purchase both Blu-ray discs and DVDs. So, to find the number of people who only buy DVDs, subtract the number of people who purchase both from the total number of consumers polled: 320 - 280 = 40 people only buy DVDs.
Therefore, 40 people only buy DVDs.
300+280-320 = 260
So, 260 bought both.
That means that 280-260=20 buy only DVDs