Final answer:
Kay will save approximately $319.82 by burning gas instead of wood in one winter.
Step-by-step explanation:
To calculate how much Kay will save by burning gas instead of wood, we need to compare the costs of burning each fuel.
To burn wood, Kay normally uses 2 cords, at a cost of $250 per cord. This means she spends 2 * $250 = $500 on wood in the winter.
Next, we need to calculate the cost of burning gas. The fireplace insert burns 33,000 BTU per hour and Kay will burn the fireplace for 5 hours per day for 120 days. This is a total of 33,000 * 5 * 120 = 19,800,000 BTU in one winter.
Since 1 therm is 100,000 BTU, Kay will burn 19,800,000 / 100,000 = 198 therms of gas.
The cost of gas is $0.91 per therm, so Kay will spend 198 * $0.91 = $180.18 on gas in the winter.
To calculate her savings, we subtract the cost of gas from the cost of wood: $500 - $180.18 = $319.82.
Kay will save approximately $319.82 by burning gas instead of wood in one winter.