Answer:
D
Step-by-step explanation:
Since x is the measure of the third angle and all 3 angles are congruent then
All 3 angles have a measure of x
The sum of the 3 angles in a triangle = 180°, this
x + x + x = 180 ← is the required equation
3x = 180 ( divide both sides by 3 )
x = 60
Answer:
C and D
Step-by-step explanation:
16/5 is roughly equal to 3.2. Is that what your are asking?
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:

<span>22.5+7 (n-3.4)=19.8n
We simplify the equation to the form, which is simple to understand
<span>22.5+7(n-3.4)=19.8n
Reorder the terms in parentheses
<span>22.5+(+7n-23.8)=19.8n
Remove unnecessary parentheses
<span>+22.5+7n-23.8=+19.8n
We move all terms containing n to the left and all other terms to the right.
<span>+7n-19.8n=-22.5+23.8
We simplify left and right side of the equation.
<span><span>-12.8n=+1.3
</span>We divide both sides of the equation by -12.8 to get n.
<span>n=-0.1015625</span></span></span></span></span></span></span>