How much metal is needed to cast a cubical metal box with outer side 10 inches long if the thickness of its walls should be exa
ctly 2 inches?
1 answer:
Notice the picture below
so... a cube has all sides equal, so is just a rectangular prism with equal sides
and a rectangular prism is just 6 rectangles stacked up to each other at the edges
now, notice in the graph at the bottom, one of the rectangles with a thickness of 2inches
so... just get the volume of each, and add them up, that's how much metal is needed
so... a cube has all sides equal, so is just a rectangular prism with equal sides
and a rectangular prism is just 6 rectangles stacked up to each other at the edges
now, notice in the graph at the bottom, one of the rectangles with a thickness of 2inches
so... just get the volume of each, and add them up, that's how much metal is needed
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ANSWER
The correct answer is C
EXPLANATION
We want to find the quotient:
We multiply by the reciprocal of the second fraction:
We cancel out the common factors to obtain:
We multiply to get
This simplifies to :
The correct answer is C
This problem can be solved using equivalent fractions. The first step in resolving this problem is to realize that fractions are best compared when they both have the same denominator. In this case, I will choose to make that common denominator 100. There is no need to rewrite the fraction as the denominator for this fraction is already 100. The fraction
. This is achieved by multiplying both the numerator and denominator by 20. Now that the two fractions have the same denominator, we can easily see that
is greater than
because it is greater than its equivalent fraction.