So mean is pretty easy to calculate; you just add everything up and divide by the number of things you added. Variance is pretty tricky because it involves subtracting the mean from each number, squaring that, adding all of the numbers up, and then dividing by the number of things. Then standard deviation is just the square root of the variance. Although some might enjoy spending hours figuring these out (I actually had to take a class where we only did this and stuff like it), most of us who use statistical tests do not want to waste our time on it. It is for that reason that there are websites that will compute all of these and all you have to do is put in the numbers. A pretty good one is:
http://www.calculator.net/standard-deviation-calculator.html
This one will calculate these and almost any other tests you need.
Now to your problem, if we add all of them up and divide by N (the # of things added), then we will get a mean of (μ=$5.10). From this, we can do further descriptive statistics. Standard Variance of the sample was calculated to (s^2=0.254). If we take the square root of the variance, we get a standard deviation of (s=0.504). I hope that this helps you with this problem and I hope that I helped for future problems by introducing the variance and standard deviation calculator to you!
Let the number be x,
(1/2)x=1+(1/3)x
Solving for x,
(1/2)x-(1/3)x=1+(1/3)x-(1/3)x
(1/2)x-(1/3)x=1
(1*3/6)x-(1*2/6)x=1
(3/6)x-(2/6)x=1
(1/6)x=1
6*(1/6)x=6*1
Therefore, x=6
Answer:
Step-by-step explanation:
See attachment
Answer:
Ah yes, one of my favorite topics.
Step 1: Which ever fraction comes first, you will solve it first. For this question, focus on doing 
first. Afterwards, do 
Step 2: First one equals to 1.125. Next, find the LCD (lowest common dominator, which is 10). 
Step 3: 1.125+3/10
Answer:
A = choosing a red marble
B = choosing a green marble
Probability of A happening = P(A) = 5/(3+5+4) = 5/12
Probability of B happening = P(B) = 4/(3+5+4) = 4/12
Probability of either happening = P(A) + P(B) = 5/12 + 4/12 = 7/12
The key word in their question is red OR green and that is why we add the two probabilities. If they ask the probability of them both happening (if they said red AND green), you would multiply P(A)*P(B).
