Acouple plans to have 3 children. the gender of each child is equally likely. design a simulation involving 35 trials that you can use to model the genders of the children. write your answers as numbers.

Computers eat this sort of stuff up for a snack. If you like I can run the simulation for you. In the meantime, you can set up the simulation yourself. It is like flipping a coin 35 times. 

Child 1    Child 2    Child 3
M              M            M
M              M            F
M              F             M
M              F             F
F               M            M
F               M            F
F              F              M
F              F              F

No Males                 1/8
1 Male 2 females     3/8
2 Males 1 female     3/8    
No Females             1/8

Now you need to deal with the 35 

Take each of the probabilities and multiply by 35

No males = 1/8 * 35 = 4.375
1 M 2 Fe  = 3/8 * 35 = 13.125
2 M 1 Fe  = 3/8 * 35 = 13.125
3 M          = 1/8 * 35 =  4.375
Total = 35.

Just in case you are interested, I'll post a simulation of a million trials to see how close they come to the theoretical expectations. I do this in comments a bit later.
It should come to about 1/8, 3/8 3/8 and 1/8. We'll see if it does.

The simulation you seek would be coin tossing. Heads and Tails will give exactly the same results.

It is 5.8 you add all of the up to equat 180 then solve the equation