Finding the Fourth Proportional to 1,355.31, 1,869.12 and 1,056.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.31 : 1,869.12 = 1,056.63 : x
2. Step 2: Convert to fraction form
   1,355.31/1,869.12 = 1,056.63/x
3. Step 3: Cross multiply
   1,355.31x = 1,869.12 × 1,056.63
4. Step 4: Simplify right side
   1,355.31x = 1,974,968.27
5. Step 5: Solve for x
   x = 1,974,968.27/1,355.31
6. Step 6: Final answer
   x = 1,457.21