Finding the Fourth Proportional to 1,428.48, 1,971.54 and 839.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.48 : 1,971.54 = 839.37 : x
2. Step 2: Convert to fraction form
   1,428.48/1,971.54 = 839.37/x
3. Step 3: Cross multiply
   1,428.48x = 1,971.54 × 839.37
4. Step 4: Simplify right side
   1,428.48x = 1,654,851.53
5. Step 5: Solve for x
   x = 1,654,851.53/1,428.48
6. Step 6: Final answer
   x = 1,158.47