It is given in the question that
Anna buys 12 pens and 20 pencils for a total cost of $16. One pen costs $0.40 more than a pencil.
Let the cost of pencil is $ x .
Therefore cost of pen is
According to the question
Distributing 12 and combining like terms, we will get
Therefore cost of pencil is $0.35 and cost of pen is
Let X be a discrete random variable with geometric distribution.
Let x be the number of tests and p the probability of success in each trial, then the probability distribution is:
P (X = x) = p * (1-p) ^ (x-1). With x = (1, 2, 3 ... n).
This function measures the probability P of obtaining the first success at the x attempt.
We need to know the probability of obtaining the first success at the third trial.
Where a success is defined as a customer buying online.
The probability of success in each trial is p = 0.3.
So:
P (X = 3) = 0.3 * (1-0.3) ^ (3-1)
P (X = 3) = 0.147
The probability of obtaining the first success at the third trial is 14.7%
D=y2-y1
D+y1= y2-y1+y1 add y1 to both sides to cancel it out.
D+y1=y2 that drops -y1 for the right side but the left remains.
And that's your answer.
The square root of 225 is 15 :)
