Answer: D) 20
=====================================
Explanation:
There are...
- 109 people who shopped at a big box store only
- 107 people who shopped online only
- 34 people who shopped at locally owned stores only
- 57 people who shopped big box and online, but not locally owned stores
- 17 people who shopped big box and locally owned, but not online
- 38 people who shopped online and locally owned, but not big box stores.
- 18 people who did all three
Add up these values and we get
109+107+34+57+17+38+18 = 380
This means there are 380 people who shopped either
- 1 category only (big box, online or locally owned)
- 2 categories only, or,
- all 3 categories
There were 400 people surveyed, so that leaves 400-380 = 20 people who didnt use any of the three categories when it came to shopping.
