Answer: 39 weeks
Step-by-step explanation:
Given
The average temperature is [tex]85^{\circ}F[/tex] or higher
A year has 52 weeks
It is given 25% of the time-temperature is above [tex]85^{\circ}F[/tex]
So, in the remaining 75% of the weeks, the average temperature is less than [tex]85^{\circ}F[/tex]
No of weeks can be determined by
[tex]\Rightarrow 75\%\ \text{of}\ 52\\\\\Rightarrow \dfrac{75}{100}\times 52=39\ \text{weeks}[/tex]