In order to calculate the percentage that enjoy New Years Eve only, we can use the diagram and formula below:
Using F to represent Fourth of July, N to represent New Years Eve and M to represent Memorial Day, the formula is:
![P(N\text{ only})=P(N)-P(F\text{ and }N)-P(M\text{ and }N)+P(all\text{ }three)](https://img.qammunity.org/2023/formulas/mathematics/college/p41y4elrqe5piiox69vs9jh0apgjfcny8s.png)
From the given data, we have:
P(N) = 28% = 0.28
P(F and N) = 18% = 0.18
P(M and N) = 12% = 0.12
P(all three) = 5% = 0.05
So P(N only) is:
![\begin{gathered} P(N\text{ only})=0.28-0.18-0.12+0.05\\ \\ P(N\text{ only})=0.03=3\% \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/kqacnmsapjy42qhksoq72gxs0nmsh6bs01.png)