a)
And replacing we got:
b)
And adding we got:
c)
And replacing we got:
Step-by-step explanation:
Let X the random variable of interest "numebr of times that an alarm is triggered", on this case we now that:
The probability mass function for the Binomial distribution is given as:
Where (nCx) means combinatory and it's given by this formula:
Part a
We want to find this probability:
And replacing we got:
Part b
And adding we got:
Part c
And replacing we got:
0.8 or 4/5
Step-by-step explanation:1/5 x 4 = 4/5
And to check your work
4/5 / 4 = 1/5