Finding the Fourth Proportional to 1,311.61, 1,969.35 and 875.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.61 : 1,969.35 = 875.57 : x
2. Step 2: Convert to fraction form
   1,311.61/1,969.35 = 875.57/x
3. Step 3: Cross multiply
   1,311.61x = 1,969.35 × 875.57
4. Step 4: Simplify right side
   1,311.61x = 1,724,303.78
5. Step 5: Solve for x
   x = 1,724,303.78/1,311.61
6. Step 6: Final answer
   x = 1,314.65