Answer:
Step-by-step explanation:
The desired formula parameters for Newton's Law of Cooling can be found from the given data. Then the completed formula can be used to find the temperature at the specified time.
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<h3>Given:</h3>
<h3>Find:</h3>
k
T(4)
<h3>Solution:</h3>
Filling in the given numbers, we have ...
185 = 68 +(208 -68)e^(-k·3)
117/140 = e^(-3k) . . . . . subtract 68, divide by 140
ln(117/140) = -3k . . . . . . take natural logarithms
k = ln(117/140)/-3 ≈ 0.060
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The temperature after 4 minutes is about ...
T(4) = 68 +140e^(-0.060·4) ≈ 68 +140·0.787186
T(4) ≈ 178.205
After 4 minutes, the final temperature is about 178 °F.
Answer:
367
Step-by-step explanation:
367 because it is positive
Answer:
30 hours
Step-by-step explanation:
Distance = Speed * Time
We can use that formula to plug in the numbers given.
1778mi = 61.7mph * Time
1778/61.7 = 28.817 (approx.)
So the answer will be about 30 hours
Answer: 18
Step-by-step explanation: Well <u><em>percent</em></u> means <em>over 100</em> so we can set up an equation for this problem by reading it from left to right.
<em>What</em> means <em>x</em>, <em>is</em> means <em>equals</em>, <em>30%</em> is <em>30/100</em>, <em>of</em> means <em>times</em> <em>250</em>.
Simplifying on the right side of the equation,
notice that 30/100 reduces to 3/10.
So we have x = 3/10 · 60. Think of the 60 as 60/1 so we can cross-cancel the 60 and 10 to 6 and 1 and we have x = 
or <em>x = 18</em>.
Now let's check our answer back in the original problem to see if it makes sense. We have <em>18 is 30% of 60</em>.
Well we know that 100% of 60 would be 60 so 30% of 60 should be alot less than 60 so 18 seems to make sense as a pretty good answer.
Step-by-step explanation:
49 = -16t^2 + 56t
-16t^2 + 56t -49 = 0
(-4t +7) (4t -7) = 0
-4t+7 =0
t = 7/4
