Devin is making a candle by pouring melted wax into a mold in the shape of a square pyramid. Each side of the base of the pyramid is 30 mm and the height of the pyramid is 18 mm. To get the wax for the candle, Devin melts blocks of wax that are each 8 mm by 6 mm by 5 mm. How many of the wax cubes will Devin need in order to make the candle? Show all formulas and calculations used to arrive at your answer

9514 1404 393

  23

Step-by-step explanation:

The volume of the square pyramid with base of side length s and height h is ...

  V = 1/3s²h

  V = 1/3(30 mm)²(18 mm) = 5400 mm³

The volume of a block of wax is ...

  V = LWH

  V = (8 mm)(6 mm)(5 mm) = 240 mm³

Then the number of blocks of wax required for a candle is ...

  (5400 mm³/candle)/(240 mm³/block) = 45/2 blocks/candle

The candle is equal to the volume of 22.5 blocks of wax. We presume Devin will want to melt whole blocks, so ...

Devin needs 23 blocks of wax to make the candle.

-3

step-by-step explanation:

a drawing really does here:

so i draw the horizontal line y=2 and the vertical line x=-2 at this intersection i put b (this is where my right angle is going to be).   so point b is at (-2,2).   point a is 5 units long and is also on y=2 so this point has to be (3,2) or (-7,2) -doesn't matter i will go with (3,2).

now we know c is at (-2,y) we don't know the y yet bet we know that c is on x=-2.

we have the area of the triangle is .5bh=12.5

we know the base length is 5 (ab)

we have the height is (2-y) if you look at your

plug in

.5(5)(2-y)=12.5

solve for y to get the y-coordinate for c

2.5(2-y)=12.5

divide both sides by 2.5 giving:

2-y=5

now subtract 2 on both sides

-y=3

y=-3