help please

#1
Hello everyone,

I would appreciate any help regarding the following problem:

The following table represents the probability distribution of activities mothers of K-5 children are involved in:
I showed my work below, please, guide me if I am thinking the wrong way.

X number of activities P(X)

0 0.044
1 0.084
2 0.209
3 0.325
4 ?

1) ? = 0.338 because the total probabilities is 1

2) find the expected value?
x= 2.829
or Y with a bar= 0.0829x +0.0342

3) standard of deviation: 1.118

I am very thankful for any input