Finding the Fourth Proportional to 1,428.71, 1,971.54 and 839.03

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.71 : 1,971.54 = 839.03 : x
2. Step 2: Convert to fraction form
   1,428.71/1,971.54 = 839.03/x
3. Step 3: Cross multiply
   1,428.71x = 1,971.54 × 839.03
4. Step 4: Simplify right side
   1,428.71x = 1,654,171.35
5. Step 5: Solve for x
   x = 1,654,171.35/1,428.71
6. Step 6: Final answer
   x = 1,157.81