Answer:
23 cards.
Step-by-step explanation:
After Monday, Esteban has 12 cards.
After Tuesday, Esteban has 12 + 24 = 36 cards.
He gave to his sister x cards.
36 - x = 13
36 = 13 + x
23 = x
Answer:
They can either decrease the confidence level or increase the sample size, that is, survey more students.
Step-by-step explanation:
The width of a confidence interval is given by:

In which z is the critical value correponding to the confidence level(higher confidence level, higher z is),
is the standard deviation of the population and n is the size of the sample.
The students realize that this interval contains a large margin of error. What can they do to make a narrower interval?
Looking at the formula for M, they can either decrease the confidence level or increase the sample size, that is, survey more students.
To solve an addition problem, you simply add one number to the other. For example,
If I want to add 4 to 5, I would write the equation 4 + 5 = 9.
To solve a subtraction problem, you simply take a number away from another. For example,
If I want to take 5 away from 9, I would write the equation 9 - 5 = 4.
Hope I helped! :)