Answer:

Step-by-step explanation:
When the first draw is done there are 9 red balls in a sample size of 21. So there probability of drawing a red ball will be 
When the second draw is done, there will be 12 yellow balls in a sample size of 20 since the first ball will not have been replaced into the bag. So the chance of someone drawing the second ball in the second draw is 
The probability of them happening in this order is the product of both probabilities:

5n = 3(n + 2) + 10
5n = 3n + 16
12n = 16
n = 8
8 is smaller integer and 10 is the larger.
28:35
Those are divisible by 7 so divide both sides by seven
the answer is 4:5
Answer:
y= -40
Step-by-step explanation:
Answer:
11.44% probability that exactly 12 members of the sample received a pneumococcal vaccination.
Step-by-step explanation:
For each adult, there are only two possible outcomes. Either they received a pneumococcal vaccination, or they did not. The probability of an adult receiving a pneumococcal vaccination is independent of other adults. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
70% of U.S. adults aged 65 and over have ever received a pneumococcal vaccination.
This means that 
20 adults
This means that 
Determine the probability that exactly 12 members of the sample received a pneumococcal vaccination.
This is P(X = 12).


11.44% probability that exactly 12 members of the sample received a pneumococcal vaccination.