Answer:
18.9
Step-by-step explanation:
21+(-3)-(-0.9) = 21-3+0.9 = 18+0.9 = 18.9
Answer:
76.5
Step-by-step explanation:
if the area is 76.5^2, then all you have to do is take the square root, and it is 76.5
Standard error (SE)

Or

Therefore, SE of the mean = (8)/(2) =4
Now you can see its pretty simple, its 128 but the way i got it is first you double 8 which makes 16 right then double 16 and you can see you got 32 then double 32 which makes 64 so next what you have to do is double 64 Obiously so you just double those numbers to get 128....Get it?
1.64
2. 95%
Hope this helps you.