Answer:
Step-by-step explanation:
5x3= 15
8x9=72
12x11=132
14x17=138
9x17=153
15+72+132+138+153=510
510/50=10.2= mean
Answer:

Step-by-step explanation:
Given

Required
Fill in the gaps
First, we calculate the total frequency:



The proportion (p) is calculated by:

The percentage (P) is calculated by:

For interval 7 - 8, we have:


For interval 5 - 6, we have:


So, the complete table is:

Answer:
31.25% probability that the Blair family had at least 3 girls
Step-by-step explanation:
For each children, there are only two possible outcomes. Either it was a girl, or it was not. The probability of a child being a girl is independent of any other children. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
They had 4 children.
This means that 
The probability of a child being a girl is 0.5
This means that 
Probability of at least 3 children:





31.25% probability that the Blair family had at least 3 girls

Translate the words into math and solve for x. Any questions let me know.