Q. ListenYou remove the lid of the can. What is the percent of change in the surface area of the can?about □% decreasePrevious12345678Overview
Consider Surface Area: First, let's consider the surface area of a can with a lid. The surface area of a can is made up of the area of the circular top and bottom (lids) and the area of the rectangular wrap around the side.
Circle and Rectangle Formulas: The formula for the area of a circle is A=πr2, where r is the radius of the circle. Since there are 2 lids, we would normally multiply this by 2.
Total Surface Area with Lid: The formula for the area of the rectangle that wraps around the side is A=2πrh, where h is the height of the can.
New Surface Area without Lid: So, the total surface area with the lid is Atotal with lid=2(πr2)+2πrh.
Find Percent Change: After removing the lid, we lose the area of one circle, so the new surface area is Atotal without lid=πr2+2πrh.
Substitute Values: Now we need to find the percent change. The percent change formula is (New Value−Old Value)/Old Value×100%.
Simplify Equation: Substitute the surface area values into the percent change formula: Percent Change = (2πr2+2πrh(πr2+2πrh)−(2πr2+2πrh))×100%.
Correct Mistake: Simplify the equation: Percent Change = (2πr2+2πrh)(πr2+2πrh−2πr2−2πrh)×100%.
Correct Mistake: Simplify the equation: Percent Change = (πr2+2πrh−2πr2−2πrh)/(2πr2+2πrh)×100%. This simplifies to Percent Change = (−πr2)/(2πr2+2πrh)×100%.
Correct Mistake: Simplify the equation: Percent Change = (πr2+2πrh−2πr2−2πrh)/(2πr2+2πrh)×100%. This simplifies to Percent Change = (−πr2)/(2πr2+2πrh)×100%. We can cancel out πr2 in the numerator and denominator: Percent Change = −1/(2+2h/r)×100%.
Correct Mistake: Simplify the equation: Percent Change = (πr2+2πrh−2πr2−2πrh)/(2πr2+2πrh)×100%. This simplifies to Percent Change = (−πr2)/(2πr2+2πrh)×100%. We can cancel out πr2 in the numerator and denominator: Percent Change = −1/(2+2h/r)×100%. Oops, looks like we made a mistake in the previous step. We can't cancel out πr2 in the numerator and denominator because the denominator has an additional term 2πrh. We need to correct this.
More problems from Percent of change: word problems