Answer:
9/25
Step-by-step explanation:
I used to struggle on these too, but I'll exaplain the best I can. Firstly, we know that 3 people don't have a cat or a dog, so what we do is we minus that from 25. This becomes 22. Now, we have to add the amount of people who have a cat to the amount of people who have a dog, and then minus it from 22, because that is the amount of people without double ups in the class with at least either one of the pets given. So, 16+15=31. Now, we do 31-22, which is equal to 9. Therefore, 9/25 people, (because the question asked out of random in the class), have a cat and a dog. This is because the double up are the extra amount of people who had more than one pet. Hopefully this was helpful. I'm sorry if it is not as probability is a hard topic to explain.
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(Given)