This question adds a new rule. You should simply add it to your diagram, as if it were an extra rule from the setup.
Here’s how to draw the new rule and the contrapositive:
I add both the rule and the contrapositive to the diagram. This captures the full effect of the new rule, and prevents me from forgetting about part of it.
For instance, suppose I just added the part at the left. Then if M were in, I might forget that S were out. Better to add both.
If you just added H ➞ Not S on the right, you might forget that H leads to J.
There’s no rule against having the same variable twice in a diagram. It doesn’t mean H is in the forest twice.
Here’s the contrapositive:
A is wrong. Now, if S is in, J is out.
B is CORRECT. If W is in, S is still in.
C is wrong. If M is in, S is out.
D is wrong. If J is out, S is in. And if S is in, M is out.
E is wrong. On question 9, we saw we could have up to four birds in the forest. But that was before the new rule. Now S can’t be in with J, H and M, so we can only have three.
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