Finding the Fourth Proportional to 1,145.98, 1,581.54 and 641.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.98 : 1,581.54 = 641.88 : x
2. Step 2: Convert to fraction form
   1,145.98/1,581.54 = 641.88/x
3. Step 3: Cross multiply
   1,145.98x = 1,581.54 × 641.88
4. Step 4: Simplify right side
   1,145.98x = 1,015,158.90
5. Step 5: Solve for x
   x = 1,015,158.90/1,145.98
6. Step 6: Final answer
   x = 885.84