Heron Island is a coral cay in the Great Barrier Reef. Around Heron Island (and elsewhere in Australia) there are 2 color morphs
of the reef heron, Egretta sacra, a white morph and a dark or blue morph. It is generally accepted that farther north in the southern hemisphere there are many more white than dark morphs, while farther south just the opposite is true. A preliminary study was carried out to test the hypothesis that the ratio of white to dark herons on the island was 3:1. Required:
a. A small census found 16 white morphs and 4 dark. Can the assumption of a 3:1 ratio be rejected?
b. What if the census were larger with 160 white morphs and 40 dark?
In case A, as the error would be a difference of 1, the assumption could be mantained, but in case B the difference will be bigger, showing that the ratio is not 3:1 but 4:1.
<h3><u>Ratios</u></h3>
Given that a preliminary study was carried out to test the hypothesis that the ratio of white to dark herons on the island was 3:1, but A) a small census found 16 white morphs and 4 dark, to determine if the assumption of a 3 :1 ratio could be rejected, and B) to determine the same question if the census were larger with 160 white morphs and 40 dark, the following calculations must be made:
A)
3 + 1 = 4
16 + 4 = 20
4 = 20
3 = X
60 / 4 = X
15 = X
Therefore, as the error would be a difference of 1, the assumption could be mantained.
B)
3 + 1 = 4
160 + 40 = 200
150 = 3:1
In this case, the difference will be bigger, showing that the ratio is not 3:1 but 4:1.
