Given:
Total number of students = 27
Students who play basketball = 7
Student who play baseball = 18
Students who play neither sports = 7
To find:
The probability the student chosen at randomly from the class plays both basketball and base ball.
Solution:
Let the following events,
A : Student plays basketball
B : Student plays baseball
U : Union set or all students.
Then according to given information,
![n(U)=27](https://img.qammunity.org/2022/formulas/mathematics/high-school/ak7pq4y7x6nah8c4u55443ed2xluz8nl6o.png)
![n(A)=7](https://img.qammunity.org/2022/formulas/mathematics/high-school/8k8sjj28ng2o01zx858ns2ej57n2475b33.png)
![n(B)=18](https://img.qammunity.org/2022/formulas/mathematics/high-school/tf6gaoh9p49bo23q1c85vwfsfdrtlek74d.png)
![n(A'\cap B')=7](https://img.qammunity.org/2022/formulas/mathematics/high-school/zxy1phs3qx3tzvjc4w9p78zg4gw9rb68c1.png)
We know that,
![n(A\cup B)=n(U)-n(A'\cap B')](https://img.qammunity.org/2022/formulas/mathematics/high-school/slortwne34dtj4yqmkxn671n6n35qpeuvs.png)
![n(A\cup B)=27-7](https://img.qammunity.org/2022/formulas/mathematics/high-school/ikelgsm515d9b2k3u0v7ykhv4laugnpv36.png)
![n(A\cup B)=20](https://img.qammunity.org/2022/formulas/mathematics/high-school/hhbejcztfi53y75ox2qelcppnwftp51vuj.png)
Now,
![n(A\cup B)=n(A)+n(B)-n(A\cap B)](https://img.qammunity.org/2022/formulas/mathematics/high-school/opwv182tu4q75jd4xrv4g25slevdyhr2yy.png)
![20=7+18-n(A\cap B)](https://img.qammunity.org/2022/formulas/mathematics/high-school/natbs9nc2euouhcowro7oxlc0wjtp1c3z6.png)
![n(A\cap B)=7+18-20](https://img.qammunity.org/2022/formulas/mathematics/high-school/7p78egg0eo2sbe2u637hnuop7vew0ykyie.png)
![n(A\cap B)=25-20](https://img.qammunity.org/2022/formulas/mathematics/high-school/pqfe1wvumzb8xrfldmbl48hjchjioo5xno.png)
![n(A\cap B)=5](https://img.qammunity.org/2022/formulas/mathematics/high-school/c3ko59ewwp3jrrijxbdfv37r9wfrl8r4rf.png)
It means, the number of students who play both sports is 5.
The probability the student chosen at randomly from the class plays both basketball and base ball is
![\text{Probability}=\frac{\text{Number of students who play both sports}}{\text{Total number of students}}](https://img.qammunity.org/2022/formulas/mathematics/high-school/erqta363pknuinuqqcliobyut5ufk7bj7e.png)
![\text{Probability}=(5)/(27)](https://img.qammunity.org/2022/formulas/mathematics/high-school/40crm44quixjhqqwosoiqoq4z76gojzrd7.png)
Therefore, the required probability is
.