Question 13955: I need some help on solving this problem: The vertical blue stripe in the bristles of the toothbrush wears down linearly to half its original length in 90 days of regular use. After the toothebrush has been used regularly for 2 weeks and 4 days, what fractional part of this blue stripe still remains??
The choices are A) 1/10 B) 1/5 C)2/5 D)3/4 E)9/10
I need some help with this...thank you...its greatly appreciated!
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! If the toothbrush wears down to half of its length in 90 days linearly, then it will wear out the rest of the way in another 90 days, for a total of 180 days to wear completely out.
Since 2 weeks and 4 days is a total of 18 days, that would be 1/10 of the total life of the toothbrush. This means that 10% has been used up, and 90% remains. I would say the answer is E) 9/10.
R^2 at SCC
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