SOLUTION: Ashley wanted to find out if a roll of toilet paper really had 300 sheets as indicated on the label, so she unwound a roll and found that there really 300 sheets as indicated, each

Question 1144217: Ashley wanted to find out if a roll of toilet paper really had 300 sheets as indicated on the label, so she unwound a roll and found that there really 300 sheets as indicated, each sheet measures 11 cm, she got a new roll and found that a full roll has a diameter of approximately 10.5 cm and the diameter of the cardboard is 4cm, now she would like to know how many times does the paper wind around the cardboard but doesn't like to count manually by unwinding another roll and trust her mathematical ability instead
How did she do it and what answer did she get?
A)-125
B)-145
C)-180
D)-225
Answer by greenestamps(13198) (Show Source): You can put this solution on YOUR website!

The diameter of the first winding is 4cm; the diameter of the last winding is 10.5cm. The diameter of an average winding is the average of those two diameters, 7.25cm.

The length of the average winding is pi times the diameter of the average winding.

The total length of the roll is 300 times the length of one sheet.

The number of windings is the total length of the roll, divided by the length of the average winding.

You can do the calculations.

The answer is very close to one of the given answer choices.
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