Answer:
The probability that 8 mice are required is 0.2428.
Step-by-step explanation:
Given : A scientist inoculates mice, one at a time, with a disease germ until he finds 3 that have contracted the disease. If the probability of contracting the disease is two sevenths.
To find : What is the probability that 8 mice are required? The probability that that 8 mice are required is nothing ?
Solution :
Applying binomial distribution,

Where, p is the probability of success 
q is the probability of failure q=1-p, 
n is total number of trials n=8
r=3
Substitute the values,




Therefore, the probability that 8 mice are required is 0.2428.
Yes because you are multiplying 3 z’s and also 3z’s
2 + d = 2 - 3(d- 5) - 2
First, cancel 2 on both sides. / Your problem should look like:
Second, expand. / Your problem should look like:
Third, simplify -3d + 15 - 2 to get -3d + 13. / Your problem should look like:
Fourth, add 3d to both sides. / Your problem should look like:
Fifth, add d + 3d to get 4d. / Your problem should look like:
Sixth, divide both sides by 4. / Your problem should look like:

Answer as fraction:

Answer as decimal: