Finding the Fourth Proportional to 1,385.51, 1,911.53 and 861.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.51 : 1,911.53 = 861.50 : x
2. Step 2: Convert to fraction form
   1,385.51/1,911.53 = 861.50/x
3. Step 3: Cross multiply
   1,385.51x = 1,911.53 × 861.50
4. Step 4: Simplify right side
   1,385.51x = 1,646,790.03
5. Step 5: Solve for x
   x = 1,646,790.03/1,385.51
6. Step 6: Final answer
   x = 1,188.58