Based on the information given, the depth will be 5.86 cm.
From the information given, the tank whose bottom is a mirror is filled with water to a depth of 20.6 cm and small fish floats motionless 7.80 cm under the surface of the water.
Based on the information given, the depth will be calculated thus:
= 7.80/d = 1.33
1.33d = 7.80
d = 7.80/1.33
d = 5.86 cm.
In conclusion, the apparent depth of the fish when viewed at normal incidence to the water is 5.86 cm.
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