Finding the Fourth Proportional to 1,538.83, 2,123.58 and 840.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,538.83 : 2,123.58 = 840.21 : x
2. Step 2: Convert to fraction form
   1,538.83/2,123.58 = 840.21/x
3. Step 3: Cross multiply
   1,538.83x = 2,123.58 × 840.21
4. Step 4: Simplify right side
   1,538.83x = 1,784,253.15
5. Step 5: Solve for x
   x = 1,784,253.15/1,538.83
6. Step 6: Final answer
   x = 1,159.49