Answer:
We want to construct a confidence interval at 99% of confidence, so then the significance level would be 
and the value of 
. And for this case since we know the population deviation is not appropiate use the t distribution since we know the population deviation and the best quantile assuming that the population is normally distributed is given by the z distribution.
And if we find the critical value in the normal standard distribution or excel and we got:
And we can use the following excel code:
"=NORM.INV(0.005,0,1)"
Step-by-step explanation:
For this case we have the following info given:
We want to construct a confidence interval at 99% of confidence, so then the significance level would be and the value of . And for this case since we know the population deviation is not appropiate use the t distribution since we know the population deviation and the best quantile assuming that the population is normally distributed is given by the z distribution.
And if we find the critical value in the normal standard distribution or excel and we got:
And we can use the following excel code:
"=NORM.INV(0.005,0,1)"
Answer: 
* Hopefully this helps:) Mark me the brainliest:)!!
Answer:
Correct option is A
Since it is an equilateral triangle, the lengths of the sides are equal
So, x+3 y=3 x+2 y−2=4 x+
2
1
y+1
x+3 y=3 x+2 y−2
y=2 x−2
2 x−y=2 ...(1)
Also, 4 x+
2
1
y+1=x+3 y
8 x+y+2=2 x+6 y
6 x+2=5 y
6 x−5 y=−2 ...(2)
Multiplying e q(1) by 5 we get,
10 x−5 y=10 ...(3)
Subtracting e q(2) from e q(3) we get,
4 x=12⇒x=3
y=2 x−2=4
The length of one side of equilateral triangle = x+3 y =3+3(4)=15 units
