Well,you have the answer on your paper already...
Here you go. I hope this will help
Answer:
40% profit
Step by step Explanation:
Profit percentage
=( profit/cost price) * 100
0.2 = profit/cost
10+15+20+25+30= 100
Let's assume the cost price of the items is $1 each
Cost price total= $100
Profit made when buyer of 20 toffe didn't say was
0.2=profit/cost
0.2*100 =$20
If the$ 20 paid.
Total profit = $40
So percentage profit now
40/100 * 100 = 40%
Let
x------> the length side of the square base of the box
y-------> the height of the box
we know that
volume of the box=b²*h
b=x
h=y
volume=256 cm³
so
256=x²*y------>y=256/x²--------> equation 1
<span>The amount of material used is directly proportional to the surface area, so we will minimize the amount of material by minimizing the surface area.</span>
surface area of the cardboard=area of the base+perimeter of base*height
area of the base=x²
perimeter of the base=4*x
height=y
surface area=x²+4x*y-----> equation 2
substitute equation 1 in equation 2
SA=x²+4x*[256/x²]-----> SA=x²+1024/x
step 1
find the first derivative of SA and equate to zero
2x+1024*(-1)/x²=0------> 2x=1024/x²----> x³=512--------> x=8 cm
y=256/x²------> y=256/8²-----> y=4 cm
the answer is
the length side of the square base of the box is 8 cm
the height of the box is 4 cm
