Answer: im super sorry i just need points
Step-by-step explanation:
Answer: 271
Step-by-step explanation:
The formula we use to find the sample size is given by :-
, where is the two-tailed z-value for significance level of
p = prior estimation of the proportion
E = Margin of error.
If prior estimation of the proportion is unknown, then we take p= 0.5 , the formula becomes
Given : Margin of error : E= 0.05
Confidence level = 90%
Significance level
Using z-value table , Two-tailed z-value for significance level of
Then, the required sample size would be :
Simplify,
Hence, the required minimum sample size =271
The area of a triangle is hb/2, we are told the base but not the side lengths. The side length can be found using the pythagorean theorem.
s^2=(b/2)^2+h^2
The height can be found from the area because:
A=bh/2 so
h=2A/b then our pythagorean identity becomes:
s^2=(b/2)^2+(2A/b)^2
s^2=b^2/4+4A^2/b^2 or a little more neatly
s^2=(b^4+15A^2)/(4b^2), we were told A=150 and b=12 so
s^2=358236/576
s=√(358236/576) ft
s≈24.939 to nearest thousandth (which means that they actually rounded wrong because that's...
s≈24.9 to nearest tenth (they must have made earlier rounding somewhere in the earlier calculations, that's why you use symbols until the final calculation :P)
Anyway, they rounded to 25.0
It would be 70% of 400
490(.7) = 280