Finding the Fourth Proportional to 1,428.21, 1,971.54 and 868.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.21 : 1,971.54 = 868.77 : x
2. Step 2: Convert to fraction form
   1,428.21/1,971.54 = 868.77/x
3. Step 3: Cross multiply
   1,428.21x = 1,971.54 × 868.77
4. Step 4: Simplify right side
   1,428.21x = 1,712,814.81
5. Step 5: Solve for x
   x = 1,712,814.81/1,428.21
6. Step 6: Final answer
   x = 1,199.27