Answer:
16.68 cm
Step-by-step explanation:
Given that :
Mean , m = 15
Standard deviation, s = 2
Length of salamander that would Place it at 80% of salamander length :
P(Z ≤ x) = 0.8
Zscore equivalent to 0.8 = 0.842
Using the relation :
Zscore = (x - m) /s
0.842 = (x - 15) / 2
1.684 = x - 15
Add 15 to both sides
1.684 + 15 = x - 15 + 15
16.684 = x
Hence, x = 16.68 cm
Perhaps you mean to find the volume under

? It seems like you have to rely on calculus otherwise (in the case that you indeed mean

).
Assuming this, note that

describes the top half of a sphere with radius 8, which means the volume below this surface over the disk

is simply half the volume of the sphere. Thus the volume is
D -2, 4 is in the second quadrant because the -x brings it to the left side and the positive 4 puts it in the upper of the left side which is the second quadrant