You have the correct approximate value of k. The part after that is where things get a bit strange.
You don't plug in t = 5 again. We don't know the value of t yet. We're trying to solve for it.
We do know u(t) is 135 as we want the temperature to be 135 degrees. Plug this in and isolate t.
So
u(t) = 70+380e^(-0.1004183888t)
135 = 70+380e^(-0.1004183888t)
135-70 = 380e^(-0.1004183888t)
65 = 380e^(-0.1004183888t)
380e^(-0.1004183888t) = 65
e^(-0.1004183888t) = 65/380
e^(-0.1004183888t) = 13/76
-0.1004183888t = ln(13/76)
-0.1004183888t = -1.7657839828248
t = -1.7657839828248/(-0.1004183888)
t = 17.5842692152893
So it takes about 17.58 minutes for the item to cool to the desired temp
3(-1)-7= -10
3(0)-7= -7
3(1)-7= -4
3(2)-7= -1
3(3)-7= 2
therefore range = {-10,-7,-4,-1,2}
The people with smartphones is 2000 and the people with flipphones is 1500. the ratio is 2000:1500
Answer:
by going to the x then going straight up or down depending on where your x is on the line graph then go back to the x and go straight across to the number from it then put the y value over x value in Thats your answer simplify if you need to
