Since

, we know that

follows a Poisson distribution with parameter

.
Now assuming

denote the mean and standard deviation of

, respectively, then we know right away that

and

.
So,
Answer:
The answer is 408
Explanation:
20% of 510 is 102 and 510 - 102 is 408
Given : A submarine descends at a rate of 2.6 kilometers per hour.
If the ocean floor is 6.24 kilometers below sea level,
To Find : how long will it take the submarine to descend to the ocean floor?
Solution:
The submarine descends at a rate of 2.6 kilometers per hour.
Speed = 2.6 km/hr
The ocean floor is 6.24 kilometers below sea level,
Distance to be covered = 6.24 km
Time= Distance / Speed
= 6.24 / 2.6
= 2.4 hr
The submarine will take 2.4 hrs to descend to the ocean floor