Answer: 5 Pens!
Step-by-step explanation: 5 Pens Would Be The Answer.
Answer:
<em>Find the probability of success in a single trial and then think about the nature of the problem (when do we stop). </em>
Step-by-step explanation:
Observe that in the single trial, we have (8 4) possibilities of choosing our set of balls. If we have chosen two white balls and two black balls, the probability of doing that is simply
p=(4 2)*(4 2)/(8 4)
This is well know Hyper geometric distribution. Now, define random variable X that marks the number of trials that have been needed to obtain the right combination (two white and two black balls). From the nature of the problem, observe that X has Geometric distribution with parameter p that has been calculated above. Hence
P(X = n) = (1— p)^n-1 *( p )
<em>Find the probability of success in a single trial and then think about the nature of the problem (when do we stop). </em>
PQ = 9
QR = 28
Note, there is a Q in each line
Combine the two lines: PQ + QR = PR
plug in the numbers to corresponding variables
9 + 28 = PR
PR = 37
hope this helps
Answer:
16 days
Step-by-step explanation:
because
380-266=114
114 divided by 7= 16
