1) 4.55
2) Short hit
Step-by-step explanation:
1)
The table containing the score and the relative probability of each score is:
Score 3 4 5 6 7
Probability 0.15 0.40 0.25 0.15 0.05
Here we call
X = Miguel's score on the Water Hole
The expected value of a certain variable X is given by:

where
are all the possible values that the variable X can take
is the probability that 
Therefore in this problem, the expected value of MIguel's score is given by:

2)
In this problem, we call:
X = Miguel's score on the Water Hole
Here we have that:
- If the long hit is successfull, the expected value of X is

- Instead, if the long hit fails, the expected value of X is

Here we also know that the probability of a successfull long hit is

Which means that the probabilty of an unsuccessfull long hit is

Therefore, the expected value of X if Miguel chooses the long hit approach is:

In part 1) of the problem, we saw that the expected value for the short hit was instead

Since the expected value for X is lower (=better) for the short hit approach, we can say that the short hit approach is better.