Answer:
X 1 2 3 4 5 6
P(X) 0.115 a 0.422 0.312 0.034 0.015
If we want a probability distribution we need to satisfy two important conditions:
1) 
2) 
And using the second condition we have this:

With a the probability associated with the value of X=2 and solving for a we got:

So then for this case 
Step-by-step explanation:
Let X the random variable that represent the number of classes that a student takes
For this case we have the following probability distribution given:
X 1 2 3 4 5 6
P(X) 0.115 a 0.422 0.312 0.034 0.015
If we want a probability distribution we need to satisfy two important conditions:
1) 
2) 
And using the second condition we have this:

With a the probability associated with the value of X=2 and solving for a we got:

So then for this case 
Answer:
31%
Step-by-step explanation:
To determine the probability of obtaining 3 or any number in a roll, we divide the number of outcomes with the sample space.
probability of 3 : n = 6/64 = 3/32 = 0.09375
probability of 4 : n = 14/64 = 7/32 = 0.21875
Since, we use the conjuction "or", we therefore add up these probabilities.
n = 5/16 or 0.3125
Hope this Helps
Answer:
a=170
Step-by-step explanation:
180-6=174mil
round to 170.