Norma bought a plastic bag that contains 100 ballons the lable says that there are 20 each of blue, yellow, red, ,green and orange ballons what is the probability that the ballon will be either red or blue?

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.