Answer:
To calculate the number of hours Karl will need to paint a wall of 920 square feet, we can use the formula:
Time = Area / Rate
where:
Area is the total area of the wall (920 square feet) and
Rate is the painting rate per hour (78 square feet per hour).
Plugging in the values, we have:
Time = 920 square feet / 78 square feet per hour
Calculating this division, we find:
Time ≈ 11.79 hours
Therefore, Karl will need approximately 11.79 hours to paint a wall of 920 square feet.