Answer:
The confidence interval for the population variance of the thicknesses of all aluminum sheets in this factory is Lower limit = 2.30, Upper limit = 4.83.
Step-by-step explanation:
The confidence interval for population variance is given as below:
We are given
Confidence level = 98%
Sample size = n = 81
Degrees of freedom = n – 1 = 80
Sample Variance = S^2 = 3.23
(By using chi-square table)
[(n – 1)*S^2 / X^2 α/2, n– 1 ] < σ^2 < [(n – 1)*S^2 / X^2 1 -α/2, n– 1 ]
[(81 – 1)* 3.23 / 112.3288] < σ^2 < [(81 – 1)* 3.23/ 53.5401]
2.3004 < σ^2 < 4.8263
Lower limit = 2.30
Upper limit = 4.83.
Answer:
125.6m^2
Step-by-step explanation:
Let R be the greater radius and r be the smaller radius
Area of the sidewalk = R^2 - r^2 - This can be the expression
= 3.14
=(R^2-r^2)
=(11^2-9^2)
=(121-81)
= 40
= 3.14 x 40
Answer:
165 centimeters
Step-by-step explanation:
A pentagon has 5 sides
Each side is 33 centimeters long
5 x 33 = 165