Random variable

#1
Guys, I got this task that I couldn't solve. I will be very grateful for the detailed explanation.

Random variable x represents the number of girls in a family of four children.
1) Construct a table describing the probability distribution, then find the mean and standard deviation. (Hint: List the different possible outcomes.)
2) Is it unusual for a family of four children to consist of four girls?

I will be incredibly grateful for your help with the decision.
 
#4
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