Answer:
We have been given confidence interval 95%, mean 20 , data set 30 and standard deviation 3.
We will use the formula: 
Here,
Z-score value at 95% confidence interval is 1.96
On substituting the values in the formula to plug the values:

Now, we have a formula for marginal error:
Marginal error means your answer will be within that percentage only.
Say you have 3% marginal means your value will be within 3% real population 95% of the time.
Answer:
24 hours
Step-by-step explanation:
If 12 workers take 10 hours to build a wall, assuming they build at the same rate, it would take one worker 120 hours to build a wall.
By this logic, it would take 120/5 or 24 hours for 5 workers to build a wall
y+1=2x-3
y=2x-4
2x-3=y+1
2x-4=y
y=2x-4
2y+2=4x-6
2y=4x-8
y=2x-4
They are all the same: y=2x-4
Answer:
$513.34
Step-by-step explanation:
Mr. DeLuca used his debit card twice, each time for $27.50. This is a total of $55 spent.
$27.50 × 2 = $55
You now have to subtract the money spent from his bank balance.
$568.34 - $55 = $513.34
$513.34 was left in his bank account.