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anonymous · Answer

inital temperature is time = 0 or x = 0... calculate T(0) = 60*(1/2)^(0/30) + 20

anonymous · Answer

since you're not using logs, are you expected to use the graphing calculator to figure out the time it takes to reach 28 degrees C?

anonymous · Answer

ok, good... i love calculators!!!
your initial temp is correct.
did you graph the function?

anonymous · Answer

can you graph it with wolfram?

anonymous · Answer

lemme try...

anonymous · Answer

this is your graph with the line y=28 (the horizontal line). If you look where the two graphs intersect, it occurs somewhere between 85 and 90. http://www.wolframalpha.com/input/?i=graph+y%3D60*%281%2F2%29%5E%28x%2F30%29+%2B+20%2C+y%3D28+intersection

anonymous · Answer

if all we can do is read from the graph, yeah...

anonymous · Answer

but use your TI83 it has an intersection function...

anonymous · Answer

np..

anonymous · Answer

ok, by trial? so
|dw:1333069785470:dw|
do you mean like that?  and using your calculator try different values until you get something somewhere between 85 and 90?