Standard error (SE)

Or

Therefore, SE of the mean = (8)/(2) =4
Subtract thats how you get it
Since there is two negative signs in the original equation, you need two negative signs in the equivalent one as well.
Because one of the negatives if before the fraction, it doesn't matter if the second negative is on the 13 or on the 12.
The answer is A.
Answer:
medium
Step-by-step explanation:
The right answer is Medium, because to travel through the ear the sound wave must go through the ear drum.