R= diameter/2
answer: 8 units
10 >= 7 + 3x -4x+9<=1
-7 >= -7 - subtract 7 -9<=-9 - Subtract 9
__________ ___________
3 >=3x - divide by 3 -4x<=-8 - divide by -4
x>=1 x<=2
Answer: You need to wait at least 6.4 hours to eat the ribs.
t ≥ 6.4 hours.
Step-by-step explanation:
The initial temperature is 40°F, and it increases by 25% each hour.
This means that during hour 0 the temperature is 40° F
after the first hour, at h = 1h we have an increase of 25%, this means that the new temperature is:
T = 40° F + 0.25*40° F = 1.25*40° F
after another hour we have another increase of 25%, the temperature now is:
T = (1.25*40° F) + 0.25*(1.25*40° F) = (40° F)*(1.25)^2
Now, we can model the temperature at the hour h as:
T(h) = (40°f)*1.25^h
now we want to find the number of hours needed to get the temperature equal to 165°F. which is the minimum temperature that the ribs need to reach in order to be safe to eaten.
So we have:
(40°f)*1.25^h = 165° F
1.25^h = 165/40 = 4.125
h = ln(4.125)/ln(1.25) = 6.4 hours.
then the inequality is:
t ≥ 6.4 hours.
