Answer is 4.5 Show all
Steps below
Answer:
Let X the random variable of interest "number of tweets with no reaction", on this case we now that:
And the expected value is given by:

So we expect about 71 tweets with no reaction for this case.
Step-by-step explanation:
Previous concepts
A Bernoulli trial is "a random experiment with exactly two possible outcomes, "success" and "failure", in which the probability of success is the same every time the experiment is conducted". And this experiment is a particular case of the binomial experiment.
The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".
The probability mass function for the Binomial distribution is given as:
Where (nCx) means combinatory and it's given by this formula:
Solution to the problem
Let X the random variable of interest "number of tweets with no reaction", on this case we now that:
And the expected value is given by:

So we expect about 71 tweets with no reaction for this case.
Answer: 0.07
Step-by-step explanation:
in the group, we can have only 4 persons.
we have 8 boys, and 6 girls.
We want to find the probability that in the comite we have only boys.
Ok, for the first selection, the probability of selecting a boy is equal to the number of boys divided the total number of the group ( 8 + 6 = 14) this is
p1 = 8/14.
For the second selection we do the same, but we already slected a boy, so now the number of boys is 7, and the total number of posibilities is 13.
p2 = 7/13.
for the third selection we do the same, in this case the probability is
p3 = 6/12
for the fourth selection the probability will be:
p4 = 5/11
The joint probability, of all the events happening at the same time, is equal to the product of the singular probabilities:
P = p1*p2*p3*p4 = (8/14)*(7/13)*(6/12)*(5/11) = 0.07
Answer: B) 
C) 
Step-by-step explanation:



Thus, Option B and C is giving the result 4b,
Therefore, they are the expressions that are equivalent to 4b.