Answer:
x = 2
Step-by-step explanation:

You start with the top number of each fraction and multiply them. So 2x3=6. Next you take the bottom number and multiply. So 3x4=12. That would give you a fraction of 6/12. 6 is half of 12 so 6/12 simplified is equal to 1/2. Hope this helps!
<span>Standard deviation for mean of n objects = (square root n) x s.d. for one
object.
So you need (2.8/0.5)^2 or around 32.</span>