SOLUTION: Suppose the number of symbols per minute a textbook typesetter can produce is given by p(t)= 250-120(2.8)^-.5t where t is the number of months a typesetter has been in traini

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Question 1042236: Suppose the number of symbols per minute a textbook typesetter can produce is given by
p(t)= 250-120(2.8)^-.5t where t is the number of months a typesetter has been in training.
find p(4) - we keep getting a negative number -36.85 why? it even shows 4,-36.85 on the table on TI 83 Plus
Found 2 solutions by josmiceli, MathTherapy:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I'll give it a try:
+p%28t%29+=+250+-+120%2A2.8%5E%28-5t%29+
+p%284%29+=+250+-+120%2A2.8%5E%28-.5%2A4%29+
+p%284%29+=+250+-+120%2A2.8%5E%28-2%29+
+p%284%29+=+250+-+120%2A.12755+
+p%284%29+=+250+-+15.306+
+p%284%29+=+234.694+ symbols/min
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check:
Here's the plot:
+graph%28+400%2C+400%2C+-10%2C+20%2C+-25%2C+300%2C+250+-+120%2A2.8%5E%28-.5x%29+%29+
--------------------------
Not sure where your problem is.
+p%28t%29+ is positive for all +t+%3E=+0+
Note that +2.8%5E%28-2%29+=+1+%2F+%28+2.8%5E2+%29+

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose the number of symbols per minute a textbook typesetter can produce is given by
p(t)= 250-120(2.8)^-.5t where t is the number of months a typesetter has been in training.
find p(4) - we keep getting a negative number -36.85 why? it even shows 4,-36.85 on the table on TI 83 Plus
I don't know where you're going wrong, but try this: 250-120(2.8)^(-.5*4), and you should get: