10% of 80 = 8
80 - 8 = 72
if they are 10% off, the contact lenses will cost $72
Answer:
48
Step-by-step explanation:
Answer:
the dimensions that minimize the cost of the cylinder are R= 3.85 cm and L=12.88 cm
Step-by-step explanation:
since the volume of a cylinder is
V= π*R²*L → L =V/ (π*R²)
the cost function is
Cost = cost of side material * side area + cost of top and bottom material * top and bottom area
C = a* 2*π*R*L + b* 2*π*R²
replacing the value of L
C = a* 2*π*R* V/ (π*R²) + b* 2*π*R² = a* 2*V/R + b* 2*π*R²
then the optimal radius for minimum cost can be found when the derivative of the cost with respect to the radius equals 0 , then
dC/dR = -2*a*V/R² + 4*π*b*R = 0
4*π*b*R = 2*a*V/R²
R³ = a*V/(2*π*b)
R= ∛( a*V/(2*π*b))
replacing values
R= ∛( a*V/(2*π*b)) = ∛(0.03$/cm² * 600 cm³ /(2*π* 0.05$/cm²) )= 3.85 cm
then
L =V/ (π*R²) = 600 cm³/(π*(3.85 cm)²) = 12.88 cm
therefore the dimensions that minimize the cost of the cylinder are R= 3.85 cm and L=12.88 cm
Find the surface area of her notebook.
30 + 30 + 20 + 20 = 100
Now find the surface area of the square stickers.
2 + 2 + 2 + 2 = 8
So this is the surface area of one square, now multiply it by 8.
8 * 7 = 56
This is the surface area of all the stickers, now subtract it to the surface area of the notebook:
100 - 56 = 44
So 44 centimeters of the notebook cover will still be showing.
