Question

In a room full of twenty students, three of the students have not done their homework. If you choose a student at random, what is the probability that this student has done their homework? 85% 3 20 OOO 15% 1 2

Answer 1

There is a total of 20 students in the classroom.

3 out of 20 did not make their homework, this means that 17 has done their homework.

To calculate the probability of choosing a student at random and that the student has made the homework (H) you have to calculate the quotient of students that made the homework ("success") by the total number of students

`\begin{gathered} P(H)=\frac{nº\text{successes}}{nº\text{students}} \\ P(H)=(17)/(20) \\ P(H)=0.85 \end{gathered}`

Multiply it by 100 to express the result as a percentage

`\begin{gathered} P(H)=0.85\cdot100 \\ P(H)=85 \end{gathered}`

The probability of choosing a student at random and that his student has made his homework is 85%