Finding the Fourth Proportional to 2,570.65, 3,856.17 and 721.91

Step by Step Solution

1. Step 1: Write the proportion equation
   2,570.65 : 3,856.17 = 721.91 : x
2. Step 2: Convert to fraction form
   2,570.65/3,856.17 = 721.91/x
3. Step 3: Cross multiply
   2,570.65x = 3,856.17 × 721.91
4. Step 4: Simplify right side
   2,570.65x = 2,783,820.03
5. Step 5: Solve for x
   x = 2,783,820.03/2,570.65
6. Step 6: Final answer
   x = 1,082.93