Lesson 9: Q4 looks wrong


#1

There's something wrong with problem 4 in Lesson 9. The problem reads:
Set bool_four equal to the result of not not True or False and not True

I came up with False, which it says is wrong. When I look at the hint, it says:
True or not False and False. not gets evaluated first, so we have
True or True and False.

But the hint doesn't match the problem! It has a not in the wrong place.


#2

How may we interpret this?

We're not going to expect two NOT's in a row, so brackets are implied.

not ( not True or False and not True )

We can defer that, and examine,

not True or False and not True

Without brackets, NOT is evaluated first,

False or False and False

Next AND is evaluated, then OR,

False or False

which gives, False. But, we deferred the NOT, so,

not False  =>  True

Next, let's look at the Hint.

True or not False and False

Again, no brackets means that NOT is evaluated first, giving,

True or True and False

AND is evaluated first, giving,

True or False

which is True.


#3

I have determined that the correct answer is True, but not for the reason you (or the hint) shows. First, I don't agree with your statement above that just because we don't expect 2 NOTs in a row means you should place the parentheses where you did. NOTs still take precedence, and it should look like this:

not (not True) or False and not True

But the point was that the hint didn't help because it didn't match the problem. It was showing that second NOT in front of the False.