Finding the Fourth Proportional to 1,428.95, 1,971.97 and 839.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.95 : 1,971.97 = 839.50 : x
2. Step 2: Convert to fraction form
   1,428.95/1,971.97 = 839.50/x
3. Step 3: Cross multiply
   1,428.95x = 1,971.97 × 839.50
4. Step 4: Simplify right side
   1,428.95x = 1,655,468.82
5. Step 5: Solve for x
   x = 1,655,468.82/1,428.95
6. Step 6: Final answer
   x = 1,158.52