Choose the One Alternative That Best Completes the Statement or Answers

Multiple Choice

Choose the one alternative that best completes the statement or answers the question.
-Sandy manages a ceramics shop and uses a $650 ^ { \circ } \mathrm { F }$ kiln to fire ceramic greenware. After turning off her kiln, she must wait until its temperature gauge reaches $205 ^ { \circ } \mathrm { F }$ before opening it and removing the ceramic pieces. If room temperature is $70 ^ { \circ } \mathrm { F }$ and the gauge reads $500 ^ { \circ } \mathrm { F }$ in 8 minutes, how long must she wait before opening the kiln? Assume the kiln cools according to Newton's Law of Cooling:
$$\mathrm { U } = \mathrm { T } + \left( \mathrm { U } _ { \mathrm { O } } - \mathrm { T } \right) \mathrm { e } ^ { \mathrm { kt } } .$$
(Round your answer to the nearest whole minute.)

A) 79 minutes
B) 56 minutes
C) 30 minutes
D) 39 minutes