Show that if {Ni(t), t ≥ 0} are independent Poisson processes with rate λi , i = 1, 2, then {N (t), t ≥ 0} is a Poisson process with rate λ1 + λ2 where {N (t) = N1(t) + N2(t)}

Apositive number a or the same number a increased by 50% and then decreased by 50% of the result?

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.

David estimated he had about 20 fish in his pond. a year later, there were about 1.5 times as many fish. the year after that, the number of fish increased by a factor of 1.5 again. the number of fish is modeled by f(x)=20(1.5)^x. create a question you could ask that could be answered only by graphing or using a logarithm.