Finding the Fourth Proportional to 1,428.64, 1,971.54 and 839.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.64 : 1,971.54 = 839.59 : x
2. Step 2: Convert to fraction form
   1,428.64/1,971.54 = 839.59/x
3. Step 3: Cross multiply
   1,428.64x = 1,971.54 × 839.59
4. Step 4: Simplify right side
   1,428.64x = 1,655,285.27
5. Step 5: Solve for x
   x = 1,655,285.27/1,428.64
6. Step 6: Final answer
   x = 1,158.64