The temperature of a certain cup of coffee 10 minutes it was poured was 120 degree Fahrenheit> If temperature F of the coffee t minutes after it was poured can be determined by the formula F = 120*(2^-at) + 60where F is in degree Fahrenheit and a is a constant , then the temperature of the coffee 30 minutes after it was poured was how many degree Fahrenheit?
A. 65
B. 75
C. 80
D. 85
E. 90
Steps: 1) 120 = 120*(2^-10a) + 60
2) 2= 2*(2^-10a) + 1
3) 2^1-10a = 1
4) 10a =1
How did that individual go from step 2 to 3? I am failing to see the math here. I feel like maybe I am just missing something or perhaps I was taught a different way to do this in college Algebra. Wouldn't you subtract the one and get 1= 2*(2^-10a) Then get 1/2= 2^-10a, thus a=.1 So 1/2= 2^-1. If someone could please touch on this that would be great. Thus once you plug A in and t=30 it ends up being 60+15= 75. I will show this math if someone needs it on here but i believe this has already been posted. Just confused on the algebra and would like to know. Thanks!
A. 65
B. 75
C. 80
D. 85
E. 90
Steps: 1) 120 = 120*(2^-10a) + 60
2) 2= 2*(2^-10a) + 1
3) 2^1-10a = 1
4) 10a =1
How did that individual go from step 2 to 3? I am failing to see the math here. I feel like maybe I am just missing something or perhaps I was taught a different way to do this in college Algebra. Wouldn't you subtract the one and get 1= 2*(2^-10a) Then get 1/2= 2^-10a, thus a=.1 So 1/2= 2^-1. If someone could please touch on this that would be great. Thus once you plug A in and t=30 it ends up being 60+15= 75. I will show this math if someone needs it on here but i believe this has already been posted. Just confused on the algebra and would like to know. Thanks!
