math
posted by Preston .
A bag contains red, blue, and orange marbles. If the probability of randomly selecting a red marble is 0.4 and the probability of selecting a red or blue marble is 0.9 what is the probability of selecting a red or orange marble?
In my opinion, the easiest way to solve these kinds of problems is to assume that you have 100 marbles in a bag.
If 40% are red, then 40 marbles are red.
If 90% are red or blue, then 90 marbles are red or blue.
And so forth.
that doesnt make any sense to me
Just assume that you have 100 marbles. It makes the question much easier to solve rather than assuming that you have some random number x of marbles.

4 red,4 white,4 blue
at random take out 2 , say 1 red 1 white do not replace.
what is probarbility of now picking a)blue
b)red c)white
Respond to this Question
Similar Questions

probability
A bowl contains only red marbles, blue marbles and green marbles. The probability of selecting a red marble from the bowl is 3/13. The probability of selecting a blue marble from the bowl is 2/5. There are fewer than 100 marbles in … 
math
There is a jar of 16 marbles. 4 red, 7 blue and 5 green. 1) What is the probability of selecting a red marble, REPLACING it, and then selecting a blue marble. 2) What is the probability of selecting a red marble, then SETTING IT ASIDEm … 
Math
***PS: I can't put the diagram so I type it.*** The diagram below shows the contents of a jar from which you select marbles at random. Inside the jar there is 16 marbles. Inside the jar there is 4 red marbles. 7 blue marbles. 5 green … 
statistics
a jar contains red and blue marbles. two marbles are chosen without replacement. the probability of choosing a red marble and then a blue marble is .26, and the probability of selecting a blue marble first is .43. what is the probability … 
math plz help
The contents of a jar holds 4 red marbles, 7 blue marbles, and 5 green marbles from which you select marbles at random. What is the probability of selecting a red marble, replacing it, and then selecting a blue marble? 
math 2
a bag contains 8 blue marbles 6 red marbles and 4 green marbles .What is the probability of selecting a blue marble, replacing it in the bag and then selecting a red marble ? 
math
In a jar there are 4 red marbles 5 green marbles and 7 blue marbles. 1 what us the probability of selecting a red marble replacing it and then selecting a blue marble 2 What is the probability of selecting a red marble setting it aside … 
algebra PLEASE HELP ASAP
please show me the steps that you use to solve the problem. you can also use the comment field to explain the work. QUESTION: 1. what is the probability of selecting a red marble, replacing it, and then selecting a blue marble? 
statistics
A bag contains red and blue marbles. Two marbles are drawn without replacement. The probability of selecting a red marble and then a blue marble is 0 .28. The probability of selecting a red marble on the first draw is 0.5. What is … 
math
You have 4 red marbles,5 green,7 blue. What is the probability of selecting a red marble, replacing it, and selecting a blue.What is the probability of selecting a red marble, notreplacing it, and selecting a blue. I think 1 is 1/16 …