Finding the Fourth Proportional to 1,428.56, 1,971.54 and 868.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.56 : 1,971.54 = 868.90 : x
2. Step 2: Convert to fraction form
   1,428.56/1,971.54 = 868.90/x
3. Step 3: Cross multiply
   1,428.56x = 1,971.54 × 868.90
4. Step 4: Simplify right side
   1,428.56x = 1,713,061.25
5. Step 5: Solve for x
   x = 1,713,061.25/1,428.56
6. Step 6: Final answer
   x = 1,199.15