Check Your Skills Answer Key

1. 15

   The group will be as small as possible when everyone contributes as much as they’re able to. The most anyone can contribute is $75, so assume that everyone contributes $75:

   

   However, 14 people contributing $75 would only give $1,050. Therefore, you need to round up. The smallest number of people that could be in the group is 15.

2. 2 cups

   Try the limits. If Oliver used 1 cup of oil, his recipe would require 1/2 cup of vinegar and 1 1/2 cups of water. He does not have enough vinegar. If he used 1/3 cup of vinegar, he would need 2/3 cups of oil and 1 cup of water, both of which he has. He would then have 2/3 + 1/3 + 1 = 2 cups of dressing. He cannot possibly make more dressing than this, because he does not have any more vinegar.

3. 180

   Graphically:

   

   Mathematically, you can use Total = a + b − e + f.

   Because all of the consumers eat at least one of the fruits, f = 0. So: