Question

In a class of 7, there are 5 students who forgot their lunch. If the teacher chooses 2 students, what is the probability that neither of them forgot their lunch?

Answer 1

Answer: t's going to be 1/21 becuase We can think about this problem as the probability of

2

2 events happening.

The first event is the teacher choosing one student who remembered his lunch. The second event is the teacher choosing another student who remembered his lunch, given that the teacher already chose someone who remembered his lunch .

Hint #22 / 6

The probabilty that the teacher will choose someone who remembered his lunch is the number of students who remembered their lunch divided by the total number of students:

2

7

7

2

​  .

Hint #33 / 6

Once the teacher's chosen one student, there are only

6

6 left.

Hint #44 / 6

There's also one fewer student who remembered his lunch, since the teacher isn't going to pick the same student twice.

Hint #55 / 6

So, the probability that the teacher picks a second student who also remembered his lunch is

1

6

6

1

​  .

Answer 2

The probability that neither of them forgot their lunch is 10/21 if in a class of 7, there are 5 students who forgot their lunch. If the teacher chooses 2 students.

What is probability?

It is defined as the ratio of the number of favorable outcomes to the total number of outcomes, in other words the probability is the number that shows the happening of the event.

We have:

Total number of students = 7

Number of students who forgot their lunch = 5

Total number of outcomes :

$=\rm _{7}^{}\textrm{C}_2$

$\rm = \frac{7!}{2!\times 5!}$

= 21

Total number of favorable outcome:

$=\rm _{5}^{}\textrm{C}_2$

$\rm = \frac{5!}{2!\times 3!}$

= 10

Now, the probability:

= 10/21

Thus, the probability that neither of them forgot their lunch is 10/21 if in a class of 7, there are 5 students who forgot their lunch. If the teacher selects 2 students.

Learn more about the probability here:

brainly.com/question/11234923

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