According to a survey, 75% of children of ABC Kindergarten watched cartoon on smartphone. Two children are selected at random. Let X denotes the number of children in the sample who watched cartoon on smartphone.
a. Construct a tree diagram to illustrate the above event.
b. Develop the probability distribution of X.
c. Draw a bar chart for the probability distribution.
d. Find the probability that;
i) at least one child watched cartoon
ii) none of them watched cartoon
iii) more than one of them watched cartoon.        
e. Find the expected number of children who watched cartoon and interpret your answer.
f. Calculate the standard deviation of children who watched cartoon.