Answer:

Step-by-step explanation:
Already, we are given 12% of our sample size as 24.
To find the sample size, we equate to find 100%.
Let sample size be denoted by 

Hence, the sample has 200 families.
Choice 2222222222222222222222222222222
Answer:
4
Step-by-step explanation:
He should add 4 black blocks because there are a total of 4 other blocks, and in order to have a probability of 50%, the number of black blocks needs to be equal to the total number of the other colored blocks.