Finding the Fourth Proportional to 1,085.33, 1,497.76 and 643.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.33 : 1,497.76 = 643.28 : x
2. Step 2: Convert to fraction form
   1,085.33/1,497.76 = 643.28/x
3. Step 3: Cross multiply
   1,085.33x = 1,497.76 × 643.28
4. Step 4: Simplify right side
   1,085.33x = 963,469.96
5. Step 5: Solve for x
   x = 963,469.96/1,085.33
6. Step 6: Final answer
   x = 887.72