Finding the Fourth Proportional to 1,428.59, 1,971.47 and 839.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.59 : 1,971.47 = 839.14 : x
2. Step 2: Convert to fraction form
   1,428.59/1,971.47 = 839.14/x
3. Step 3: Cross multiply
   1,428.59x = 1,971.47 × 839.14
4. Step 4: Simplify right side
   1,428.59x = 1,654,339.34
5. Step 5: Solve for x
   x = 1,654,339.34/1,428.59
6. Step 6: Final answer
   x = 1,158.02