Explanation:
As the given data is as follows.
    Height, H = 150 feet
 Heat gain = 30,000 BTU/hr,  and  Heat loss = 25000 BTU/hr
 m = mass of water heated = 700 gallons = 5810 lbs
[tex]C_{p}[/tex] is the heat capacity of water = 1 BTU/lb [tex]^{o}F[/tex] (given)
   [tex]\Delta T[/tex] = temperature difference = [tex]120^{o}F - 35^{o}F[/tex]
Heat energy required to heat 700 gal can be calculated as follows:
  Heat Required = [tex]5810 lbs \times 1 BTU/lb^{o}F \times (120^{o}F - 35^{o}F)[/tex]
Thus, water rises till [tex]120^{o}F[/tex].