1. sustittbe k = -0.501359133
and t = 5

and solve for U

is that it

2. Sounds good to me. What do you get?

3. $
U = 20 + (11 - 20)e^{(5)(-0.50)}
$

4. Uh-huh. And the result is?

5. $
U = 20 + (11 - 20)e^{-2.5}
$

$
U = 20 + (11 - 20)e^{-2.5}
$

$
U = 20 + (-9)0.0820
$

$
U = 20 + -0.738
$

$
U = 19.26200
$

is this it

6. Looks good to me.

7. And it makes sense, because it's a value closer to room temperature than the value you read off at 3 minutes. That is what you'd expect, right?

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