Answer:
23rd hours
Step-by-step explanation:
This is problem based on arithmetic progression in which our first term is 45 , and the common difference is -2
we have to find the n when the nth term is 2.
The formula for nth term of an AP is
[tex]a_{n}=a+(n-1)d[/tex]
replacing the values in the formula
[tex]a_{n}=a+(n-1)d\\2=45+(n-1)(-2)\\2=45-2(n-1)\\-43=-2(n-1)\\21.5 = n-1\\n=22.5\\[/tex]
hence at 22.5 hours it will reach 2F or we can say that after 23 hours the temperature will be below 2F
