Answer:
250 boys attended the conference.
Step-by-step explanation:
First, divide 750 by 3 (one-third of the conference is boys) and you will get 250 (number of boys). If you wanted to find the number of girls too, you would simply double 250 to get 500 girls.
ANSWER
Vertex form;

Vertex

EXPLANATION
Given:

We complete the square as follows:


The vertex form is:

The vertex is

The greatest number of groups that can be formed is 10
Using the mean concept, it is found that the mean difference between the call times and the company's average call time is given by:
<h3>What is the mean?</h3>
- The <em>mean </em>of a data-set is given by the <u>sum of all observations in the data-set divided by the number of observations</u>.
In this problem:
- The four observations are the differences between the time of each phone call and the average time.
- They are: {-2.32, -1.55, 4.79, 0.68}
Hence, the mean difference is:

Hence, option C is correct.
To learn more about the mean concept, you can take a look at brainly.com/question/13451786