Finding the Fourth Proportional to 1,192.71, 1,789.59 and 644.28

Step by Step Solution

1. Step 1: Write the proportion equation
   1,192.71 : 1,789.59 = 644.28 : x
2. Step 2: Convert to fraction form
   1,192.71/1,789.59 = 644.28/x
3. Step 3: Cross multiply
   1,192.71x = 1,789.59 × 644.28
4. Step 4: Simplify right side
   1,192.71x = 1,152,997.05
5. Step 5: Solve for x
   x = 1,152,997.05/1,192.71
6. Step 6: Final answer
   x = 966.70