There are 48 available subjects. Researchers should select 4 of them for their experiment.
We should find the number of possible different random samples. The order of the selected subjects is not important. This means that we need to find how many different combinations of subjects from total 48 are possible. A formula for the number of possible combinations of r objects from a set of n objects is: n!/r!(n-r)!. In our case n=48 and r=4:
C=48!/44!*4!=48*47*46*45*44!/44!*4!=48*47*46*45/4*3*2*1=4669920/24=
194580.

4 0

3 years ago

Sarah has two tests at school next week, a math test and a physics test. Let A represent the event that she passes her math test

koban [17]

Answer:

P(B)=0.7

Step-by-step explanation:

When the events do not affect each other, they are known as independent events. In other words, two events are independent if the outcome of the second event is not affected by the outcome of the first event.

If A and B are independent events, the probability that both events will occur is the product of the probabilities that the individual events will occur:

P(A and B)= P(A)*P(B)

In this case, P(A and B)= 0.21 and P(A)= 0.30

Replacing:

0.21=0.30*P(B)

Solving:

$\frac{0.21}{0.30} =P(B)$