Finding the Fourth Proportional to 1,990.56, 2,986.18 and 691.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,990.56 : 2,986.18 = 691.72 : x
2. Step 2: Convert to fraction form
   1,990.56/2,986.18 = 691.72/x
3. Step 3: Cross multiply
   1,990.56x = 2,986.18 × 691.72
4. Step 4: Simplify right side
   1,990.56x = 2,065,600.43
5. Step 5: Solve for x
   x = 2,065,600.43/1,990.56
6. Step 6: Final answer
   x = 1,037.70