Finding the Fourth Proportional to 1,238.50, 1,709.16 and 686.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.50 : 1,709.16 = 686.50 : x
2. Step 2: Convert to fraction form
   1,238.50/1,709.16 = 686.50/x
3. Step 3: Cross multiply
   1,238.50x = 1,709.16 × 686.50
4. Step 4: Simplify right side
   1,238.50x = 1,173,338.34
5. Step 5: Solve for x
   x = 1,173,338.34/1,238.50
6. Step 6: Final answer
   x = 947.39