Answer:
![(D)E[ X ] =np.](https://tex.z-dn.net/?f=%28D%29E%5B%20X%20%5D%20%3Dnp.)
Step-by-step explanation:
Given a binomial experiment with n trials and probability of success p,


Since each term of the summation is multiplied by x, the value of the term corresponding to x = 0 will be 0. Therefore the expected value becomes:

Now,

Substituting,

Factoring out the n and one p from the above expression:

Representing k=x-1 in the above gives us:

This can then be written by the Binomial Formula as:
![E[ X ] = (np) (p +(1 - p))^{n -1 }= np.](https://tex.z-dn.net/?f=E%5B%20X%20%5D%20%3D%20%28np%29%20%28p%20%2B%281%20-%20p%29%29%5E%7Bn%20-1%20%7D%3D%20np.)
Hey I’m sorry but I do not know the answer.
The answer is 3 because z to the y a-1
450 >_ 750 - 70x
450 >_ 750 - 70x
(subtract 750 on both sides)
-300 >_ -70x
(divide by -70 to get x alone, then flip the inequality sign)
4 2/7 <_ x
(round up to 5, you can’t have 2/7 of a person)
at least 5 people have to get off
hope this helped!