Finding the Fourth Proportional to 1,620.31, 2,236.22 and 921.73

Step by Step Solution

1. Step 1: Write the proportion equation
   1,620.31 : 2,236.22 = 921.73 : x
2. Step 2: Convert to fraction form
   1,620.31/2,236.22 = 921.73/x
3. Step 3: Cross multiply
   1,620.31x = 2,236.22 × 921.73
4. Step 4: Simplify right side
   1,620.31x = 2,061,191.06
5. Step 5: Solve for x
   x = 2,061,191.06/1,620.31
6. Step 6: Final answer
   x = 1,272.10