Finding the Fourth Proportional to 1,538.71, 2,123.42 and 840.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,538.71 : 2,123.42 = 840.09 : x
2. Step 2: Convert to fraction form
   1,538.71/2,123.42 = 840.09/x
3. Step 3: Cross multiply
   1,538.71x = 2,123.42 × 840.09
4. Step 4: Simplify right side
   1,538.71x = 1,783,853.29
5. Step 5: Solve for x
   x = 1,783,853.29/1,538.71
6. Step 6: Final answer
   x = 1,159.32