Venn Diagram: How to Use Them and When

The survey of 300 parks showed the following; 

15 had only camping 

This means that; 

20 had only hiking trails 

This means that; 

35 parks had only picnicking 

This means that; 

185 had camping and 140 camping and hiking trails 

This means that; 

But we know that; 

Additionally, 

Solving equation 1 and 2 simultaneously gives; 

125 had camping and picnicking 

This means that; 

But, 

From equation 2, we can determine VI 

210 had hiking trails 

This means that; 

Calculating VIII 

Questions 

Determine the number of parks that; 

Had at least one of these features 

Had all three features 

Did not have any of these features 

Had exactly two of these features