Assuming the n data values are independent draws from a Poisson distributed population with parameter λ , the MLE of λ from the sample is the sample mean, i.e.

Numerous proves are available online.
We have a right triangle with hypotenuse 38 and leg 34.
We want to find the other leg.
We use the Pythagorean Theorem:
Answer:
4.5 Ft
Step-by-step explanation:
1/4(18)= 4.5 Ft
0.25(18)=4.5Ft