Question

In a class of 42 students, 25 take biology,15 take history,and 18 take biology but not history.i.Draw a Venn diagram to show the informationii.find how many students take niether history nor biology

Answer 1

In the class, there is a total of 42 students.

25 take biology.

15 take history.

18 take biology but not history.

There are four situations that you have to include in the Venn diagram:

"The students take only biology"

"The students take only history"

"The students take biology and history"

"The students take neither classes"

To draw the Venn diagram, you have to make one circle for each subject, i.e. one circle for biology and one for history, and label them.

Then you have to enter the similarities between both subjects, this means, where the circles overlap, you will find the students that take both subjects.

Finally, outside the circles, you will find the students that take neither subject:

Now, you have to determine how many students are included in each part of the Venn Diagram.

1) You know that 25 students take biology and that 18 take biology but not history, to determine the number of students that take both subjects, you have to calculate the difference between both values:

$25-18=7$

7 students take biology and history.

2) 15 students take history out of these you know that 7 take also biology. To determine the number of students that take only history, you have to calculate the difference between both values:

$15-7=8$

8 students take history but not biology.

3) To determine the number of students that take neither class, you have to subtract to the total number of students, those who take only biology plus those who take only history plus those who take both classes:

$\begin{gathered} \text{Neither}=\text{Total-(only biology + only history + both)} \\ \text{Neither}=42-(18+7+8) \\ \text{Neither}=42-33 \\ \text{Neither}=9 \end{gathered}$

9 Students of the class take neither class.

Finally, you can write each value in the corresponding part of the Venn diagram:

• Inside the green circle, you have to include the 18 students that take only biology.

,

• Inside the blue circle, you have to include the 8 students that take only history.

,

• Where both circles overlap, you have to include the 7 students that take both classes.

,

• Outside the circles, you have to include the students that take neither.