In this page set word problem1 we will see the problem and how to solve the problem. Using the same method students can try to solve the given practice problem.

__Question:__

There are 40 students in a class. 20 take Chemistry and 25 take French. 8 students take both.

- Find how many students take none.
- How many are there in at least one classes?

Solution:

We will solve the problem using venn diagram. First let us write all the given information.

Universal set U = 40

Students take Chemistry C = 20

Students take French F = 25

Students take both CnF = 8

Now let us enter the information in venn diagram. Here we have universal set. So we have to draw a rectangle to represent the universal set. There are two classification C and F. For that let us draw two overlapping circles.

As there are 8 students who are taking both let us enter 8 in the overlapping area of the circles C and F. |

There are 20 students who take chemistry, but we had already entered 8 students. So we have to enter only 12(20-8=12) in chemistry only area. |

Now in French there are 25 students, but we have already entered 8 students. So we have to enter only 17(25-8=17) in French only area. |

That gives the total number of students who have taken either Chemistry or French classes. 12+8+17= 37. The number of students who had taken none is 40-37 = 3 |

From the final venn diagram we can get the answers for our questions.

- Find how many students take none.
- How many are there in at least one classes?

The answers are :

- The number of students who had taken none is
**3** - There are
**37**students in at least one class.

Practice problem:

A group of 20 college students were asked whether they are using the social net working sites. For that 8 said they use face book. 10 said they use twitter. 4 said they use both.

- Find how many are not using none?
- Find how many are using only face book and twitter?

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