Part A
There are 6 red + 4 pink = 10 counters that are red or pink.
This is out of 6+5+4 = 15 counters total.
The probability we want is 10/15 = 2/3
Answer: 2/3
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Part B
There are 4 pink out of 15 total. That leaves 15-4 = 11 that aren't pink.
Answer: 11/15
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Part C
There are 6 red counters and 15 total. That means there are 15-6 = 9 counters that aren't red.
9/15 = 3/5
Answer: 3/5
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Part D
We have 6 red + 5 blue = 11 that are red or blue this is the exact same 11 from part B. This is because if we don't have a pink counter, then it must be red or blue (there aren't any other colors left).
Answer: 11/15