Answer:
2.28%
Step-by-step explanation:
If X is the random variable that measures the time of incubation needed before hatching, we want
P(X>343)
This is the area under the normal curve whose mean is 336 hours and its standard deviation 3.5 hours to the right of the point 343. (See picture attached)
This can be done easily with the help of a computer and we find
P(X>343) = 0.0228 or 2.28%