Answer:
1) x=-1.5 , x=8 that is the answer
Answer: Our required probability is 0.99338.
Step-by-step explanation:
Since we have given that
n = 100
p = 0.200
So, 
So, we can apply normal approximation.
Mean = 20
Standard deviation = 
Since 
So, Probability that fewer than 30 but a packet after testing a free sample is given by

Hence, our required probability is 0.99338.
Answer:
2 1/2 minutes
Step-by-step explanation:
5/8 + 5/8 + 5/8 + 5/8
20/8
2 and 4/8 minutes