There are 10 students in class and the number of siblings in their families are given by {1,1,1,1,2,3,3,4,4,4}. Consider the experiment of randomly choosing one of these students and letting Y denote the number of siblings in this chosen student’s family. (a) Find the probability mass function (pmf) of Y and plot this pmf. (b) Find Pr{Y > 2}. (c) Find the mean, µ, of Y . (d) Find the standard deviation, σ, of Y . (e) Find the exact value of P(µ−2σ ≤ Y ≤ µ + 2σ}.

a. Check the attached image

b. The Pr(Y > 2) = ½

c. The mean is 2.4

d. The standard deviation is: 2.72

e. The exact value is 1 because it is certain from the given data that any probability will fall within that range.

Step-by-step explanation:

a. An image showing the step by step solution is attached.

b. P(Y > 2) = P(3) + P(4)

= 2/10 + 3/10 = 5/10 = ½

c. The mean is 2.4

d. The standard deviation is: 2.72

e. Check the attached image for the steps.

starting with:    

5 + x - 12 = 2x - 7   

5 + x - 12 - x = 2x - 7 - x (subtract x from both sides)   

5 - 12 = x - 7 (combine and cancel x's from both sides)   

5 - 12 + 7 = x - 7 + 7 (add 7 to both sides)   

0 = x (add numbers together on both sides)       

so in order for the equation to be true, x must be 0.   

trying x = -0.5   

5 + x - 12 = 2x - 7 (original equation)   

5 + -0.5 - 12 = 2(-0.5) - 7 (plug in value of x)   

5 + -0.5 - 12 = -1 - 7 (did multiplication)   

-7.5 = -8 (did addition on both sides)       

since -7.5 is obviously not equal to -8, the value of -0.5 for x is wrong.   

trying x = 0   

5 + x - 12 = 2x - 7 (original equation)   

5 + 0 - 12 = 2(0) - 7 (plug in value of x)   

5 + 0 - 12 = 0 - 7 (did multiplication)   

-7 = -7 (did addition on both sides)       

since -7 equals -7, that demonstrates that the value of 0 for x is correct.   

trying x = 1   

5 + x - 12 = 2x - 7 (original equation)   

5 + 1 - 12 = 2(1) - 7 (plug in value of x)   

5 + 1 - 12 = 2 - 7 (did multiplication)   

-6 = -5 (did addition on both sides)       

since -6 is obviously not equal to -5, the value of 1 for x is wrong.