Finding the Fourth Proportional to 1,381.61, 1,905.98 and 821.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,381.61 : 1,905.98 = 821.76 : x
2. Step 2: Convert to fraction form
   1,381.61/1,905.98 = 821.76/x
3. Step 3: Cross multiply
   1,381.61x = 1,905.98 × 821.76
4. Step 4: Simplify right side
   1,381.61x = 1,566,254.02
5. Step 5: Solve for x
   x = 1,566,254.02/1,381.61
6. Step 6: Final answer
   x = 1,133.65