How many BTUs are required to raise the temperature of a 1,500-gallon spa from 91 degrees to 102 degrees?

To determine how many BTUs are required to raise the temperature of a 1,500-gallon spa from 91 degrees to 102 degrees, you need to understand the concept of BTU (British Thermal Unit) and how it relates to water heating.

First, calculate the total temperature rise needed, which is 102 degrees - 91 degrees = 11 degrees. Next, we need to consider how many BTUs are necessary to raise the temperature of water. It takes approximately 8.34 BTUs to raise the temperature of one gallon of water by one degree Fahrenheit.

Now, using this relationship, we can find out the total BTUs needed for the entire volume of water in the spa:

1. Calculate the total BTUs for one degree change for 1,500 gallons:

1,500 gallons × 8.34 BTUs/gallon = 12,510 BTUs to raise the temperature by 1 degree.

2. For the desired temperature increase of 11 degrees:

12,510 BTUs/degree × 11 degrees = 137,610 BTUs (rounded to a more precise figure).

When looking at the options provided, the choice that most closely aligns with this calculation is 137