Answer:
do you have a photo of the figure?
Assume r= t not sure if you mistyped this.
t = 15 min
T(t) = 68 (0.5)^(15/10) = 24 Celsius
31 = (0.5)^(t/10) take ln
ln31 = (t/10) ln (0.5) + ln68
t = (ln32 - ln 68/ln0.5) * 10 = 11.3 min
Well what I would do is split the 40% into 20% so from 40% to 20% that is /2. So 32/2=16 so 20% of a number is 16, we know there is 5, 20% in 100% so multiply 16 and 5 which gives you 80. Now 25% of 80 is the same as 80*.25 or 80/4 which is 20
Your Answer 20
Just multiply 42 by 10 and that gives you 420 , so the real car has a length of 420cm or 4.2 metres :)
