Finding the Fourth Proportional to 1,081.30, 1,492.29 and 638.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,081.30 : 1,492.29 = 638.98 : x
2. Step 2: Convert to fraction form
   1,081.30/1,492.29 = 638.98/x
3. Step 3: Cross multiply
   1,081.30x = 1,492.29 × 638.98
4. Step 4: Simplify right side
   1,081.30x = 953,543.46
5. Step 5: Solve for x
   x = 953,543.46/1,081.30
6. Step 6: Final answer
   x = 881.85