Finding the Fourth Proportional to 1,428.69, 1,971.63 and 839.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.69 : 1,971.63 = 839.24 : x
2. Step 2: Convert to fraction form
   1,428.69/1,971.63 = 839.24/x
3. Step 3: Cross multiply
   1,428.69x = 1,971.63 × 839.24
4. Step 4: Simplify right side
   1,428.69x = 1,654,660.90
5. Step 5: Solve for x
   x = 1,654,660.90/1,428.69
6. Step 6: Final answer
   x = 1,158.17