Question 1004659
{{{ T(t) = 75 + 115*e^(-.042t) }}}
(a)
{{{ t = 30 }}}
{{{ T(30) = 75 + 115*e^(-.042*30) }}}
{{{ T(30) = 75 + 115*e^(-1.26) }}}
{{{ T(30) = 75 + 115*.28365 }}}
{{{ T(30) = 75 + 32.6202 }}}
{{{ T(30) = 107.6202 }}}
{{{ T(30) = 108 }}} degrees F
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(b)
{{{ T(t) = 75 + 115*e^(-.042t) }}}
{{{ 130 = 75 + 115*e^(-.042t) }}}
{{{ 55 = 115*e^(-.042t) }}}
{{{ e^(-.042t) = .47826 }}}
{{{ ln( .47826 ) = -.042t }}}
{{{ -.7376 = -.042t }}}
{{{ t = 17.562 }}}
{{{ t = 17.6 }}} min
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