Finding the Fourth Proportional to 1,577.40, 2,176.78 and 869.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,577.40 : 2,176.78 = 869.31 : x
2. Step 2: Convert to fraction form
   1,577.40/2,176.78 = 869.31/x
3. Step 3: Cross multiply
   1,577.40x = 2,176.78 × 869.31
4. Step 4: Simplify right side
   1,577.40x = 1,892,281.39
5. Step 5: Solve for x
   x = 1,892,281.39/1,577.40
6. Step 6: Final answer
   x = 1,199.62