Answer:
<em>5</em><em> players participated in the tournament.</em>
Step-by-step explanation:
In a small chess tournament, 20 matches were played.
Let us assume that n number of players participated in the tournament
As in each game 2 players play, so the number of ways they can play is,

As they played 2 games with every other participant in the tournament.
So the total number of games is,

But it is given to be 20, so





As
, so we get n=5.
Therefore, 5 players participated in the tournament.
Answer:
The answer is
A
Step-by-step explanation:
kindly find attached the solving for proper understanding and solution flow.
Given Data
the divisor= 
dividend= 
firstly for us to perform the division we need to re write the dividend and include the missing coefficient of x
dividend 
Answer:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:

Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the variable of interest of a population, and for this case we know the distribution for X is given by:
Where
and 
We are interested on this probability

And the best way to solve this problem is using the normal standard distribution and the z score given by:

If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:
