Finding the Fourth Proportional to 1,140.48, 1,573.83 and 643.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,140.48 : 1,573.83 = 643.10 : x
2. Step 2: Convert to fraction form
   1,140.48/1,573.83 = 643.10/x
3. Step 3: Cross multiply
   1,140.48x = 1,573.83 × 643.10
4. Step 4: Simplify right side
   1,140.48x = 1,012,118.99
5. Step 5: Solve for x
   x = 1,012,118.99/1,140.48
6. Step 6: Final answer
   x = 887.45