A study compared paired daytime and nighttime counts of sea trout, lake trout, and rainbow trout made by the same divers in six lakes during September 2015. Overall, they counted 127 trout during the day and 356 trout at night. The researchers speculate that trout counted at night were present during the daytime but were hidden from view. Biologists should consider that trout behavior and susceptibility to being seen might vary a great deal between daytime and nighttime, even during the summer. In some lakes, the majority of trout may not be seen during the daytime. Determine whether the study is an observational study or an experiment. Justify your answer with specific references to the information in the study.

Observational Study

Step-by-step explanation:

An experimental study is a research study in which conditions are under the direct manipulation of the investigator. We use it to mainly test the efficacy of a medical, preventive, or therapeutic measure.

In an observational study, on the other hand,  the researcher observes the effect without trying to influence the outcome in any way.

In this study, the researchers are trying to determine the paired daytime and nighttime counts of the species of fishes made by the same divers in six lakes during September 2015.

This is simply an Observational Study as nothing is done to influence the population count.

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step-by-step explanation:

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!