1. ## Ten Counters

There are 10 counters in a bag: 3 are red, 2 are blue and 5 are green.The contents of the bag are shaken before Maxine randomly chooses one counter from the bag.What is the probability that shedoesn't pick a red counter?

Let A = probability that Maxine chooses a red counter.

P(A) = 3/10

The probability that Maxine does not pick a red counter is 1 - P(A).

1 - P(A) = 1 - 3/10

1 - P(A) = (10/10) - (3/10)

1 - P(A) = 7/10

Correct?

2. ## Re: Ten Counters

Originally Posted by harpazo
There are 10 counters in a bag: 3 are red, 2 are blue and 5 are green.The contents of the bag are shaken before Maxine randomly chooses one counter from the bag.What is the probability that shedoesn't pick a red counter?
Let A = probability that Maxine chooses a red counter. P(A) = 3/10
The probability that Maxine does not pick a red counter is 1 - P(A).
1 - P(A) = 1 - 3/10
1 - P(A) = (10/10) - (3/10)
1 - P(A) = 7/10
Correct?
Yes correct.

Another approach is: seven out of ten are not red.

3. ## Re: Ten Counters

Another way to look at this is that there are 7 "not-red" counters out of 10.

4. ## Re: Ten Counters

Another one for my notes.