Finding the Fourth Proportional to 1,085.16, 1,497.72 and 643.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.16 : 1,497.72 = 643.30 : x
2. Step 2: Convert to fraction form
   1,085.16/1,497.72 = 643.30/x
3. Step 3: Cross multiply
   1,085.16x = 1,497.72 × 643.30
4. Step 4: Simplify right side
   1,085.16x = 963,483.28
5. Step 5: Solve for x
   x = 963,483.28/1,085.16
6. Step 6: Final answer
   x = 887.87