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/sci/ - Science & Math

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4007213 No.4007213 [Reply] [Original]

Non-homework math puzzle question.

Phoneline A charges $1.00 for every minute up to and including 20 minutes and 0.07¢ thereafter. Phoneline B charges 0.06¢ per minute. t is a number greater than 20 and equals the number of minutes when lines A and B are the same cost. Find t.

>> No.4007222

>basic linear equations
>puzzle

Yeah, okay, shithead, this totally isn't homework.

>> No.4007227

>>4007213
no solutions
/thread

>> No.4007231

.07(t-20) + 1 = .06t

is how you'd set up the general algebra.


the simplest way to do to this problem is just to evaluate right when the 20 minutes are up, see that B has paid $1.20 and A has only paid the first dollar. Every minute after than A is "outpacing" B by 1 cent, so in another 20 minutes he'll catch up. Therefore, 40 minutes.

>> No.4007236
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4007236

>>4007231
reading properly! can you into it, motherfucker!??
>Phoneline A charges $1.00 for every minute up to and including 20 minutes

>> No.4007244

I actually saw this in an sat practice book I saw lying around. The answer was 40, just coulsn't derivw an equation. It was free response too, so no pluging in