Finding the Fourth Proportional to 1,107.31, 1,528.17 and 641.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,107.31 : 1,528.17 = 641.56 : x
2. Step 2: Convert to fraction form
   1,107.31/1,528.17 = 641.56/x
3. Step 3: Cross multiply
   1,107.31x = 1,528.17 × 641.56
4. Step 4: Simplify right side
   1,107.31x = 980,412.75
5. Step 5: Solve for x
   x = 980,412.75/1,107.31
6. Step 6: Final answer
   x = 885.40