Answer:
A. 55 miles/hour
Step-by-step explanation:
Answer:
64 × pi m²
Step-by-step explanation:
the formulas needed for the surface area of a cone are :
base area plus the "mantle", the lateral "wall" around it.
the base area is a circle.
so, that formula is Ac = pi×r²
the "wall" formula is Aw = pi×r×s
r = radius
s = slant height = 12
the formula for the surface area of a sphere is
As = 4×pi×r²
we know now, that both surface areas are the same, and also the radius is the same for both objects.
Ac + Aw = As
pi×r² + 12×pi×r = 4×pi×r²
=>
12×pi×r = 3×pi×r²
12×pi = 3×pi×r
12 = 3×r
r = 4 m
now, we only need to use this value of r in our formulas for surface areas, like for the sphere :
4×pi×r² = 4×pi×4² = 4³×pi = 64×pi
Given:
Jake bought 3 drawing pens for $8.07.
Each pen costs the same amount.
To find:
How much did he spend for one pen?
Solution:
Let x be the cost of each pen. Then
Cost of three pens = 3x
Jake bought 3 drawing pens for $8.07.
Divide both sides by 3.
Therefore, he spend $2.69 for one pen.
Suppose that this person drives at r mph going to the mountains, and gets there in 12 hours. Returning, this person drives at (r+20) mph and gets home in 8 hours. We don't know the distance yet, but can solve for the initial speed, r, by setting
d = 12r = (r+20)(8). Solving for r, r=40 mph (going) and (40+20)mph = 60 mph (returning. Since d=12 r, d = (12 hrs)(40 mph) = 480 miles (answer).
