Answer:
The standard deviation for this distribution is 0.8660.
Step-by-step explanation:
For each coin toss, there are only two possible outcomes. Either it is heads, or it is tails. So we use the binomial probability distribution to solve this problem.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The standard deviation of the binomial distribution is:

In this problem, we have that:
In each toss, heads or tails are equally as likely, since the coin is fair. So 
Three throws, so 
What is the standard deviation for this distribution?

The standard deviation for this distribution is 0.8660.
X would be 4 so the answer is B
Assume that the number of adult tickets is a and the number of child tickets is c.
We are given that the adult ticket is sold for 20$, the child ticket is sold for 10$ and that the total is $15,000. This means that:
20a + 10c = 15,000 ..........> equation I
We are also given that number of child tickets is 3 times that of adult's. This means that:
c = 3a .........> equation II
Substitute with equation II in equation I to get a as follows:
20a + 10c = 15,000
20a + 10(3a) = 15,000
20a + 30a = 15,000
50a = 15,000
a = 300 tickets
Substitute with the value of a in equation II to get c as follows:
c = 3a
c = 3(300)
c = 900 tickets
Based on the above calculations,
number of child tickets = 900 ticket
number of adult tickets = 300 ticket
Answer:
20 students
Step-by-step explanation:
You first have to add the number of students all up and you get 200.Then you do cross multiplication.
40/200 x s/100=
40x100= 4000=
200xs= 200s=
200s/200=
4000/200=
20=
The rate would be 40 questions per hour