Finding the Fourth Proportional to 2,780.57, 4,171.52 and 931.69

Step by Step Solution

1. Step 1: Write the proportion equation
   2,780.57 : 4,171.52 = 931.69 : x
2. Step 2: Convert to fraction form
   2,780.57/4,171.52 = 931.69/x
3. Step 3: Cross multiply
   2,780.57x = 4,171.52 × 931.69
4. Step 4: Simplify right side
   2,780.57x = 3,886,551.88
5. Step 5: Solve for x
   x = 3,886,551.88/2,780.57
6. Step 6: Final answer
   x = 1,397.76