Finding the Fourth Proportional to 1,665.40, 2,497.86 and 691.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,665.40 : 2,497.86 = 691.72 : x
2. Step 2: Convert to fraction form
   1,665.40/2,497.86 = 691.72/x
3. Step 3: Cross multiply
   1,665.40x = 2,497.86 × 691.72
4. Step 4: Simplify right side
   1,665.40x = 1,727,819.72
5. Step 5: Solve for x
   x = 1,727,819.72/1,665.40
6. Step 6: Final answer
   x = 1,037.48