Finding the Fourth Proportional to 1,210.50, 1,670.31 and 686.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,210.50 : 1,670.31 = 686.43 : x
2. Step 2: Convert to fraction form
   1,210.50/1,670.31 = 686.43/x
3. Step 3: Cross multiply
   1,210.50x = 1,670.31 × 686.43
4. Step 4: Simplify right side
   1,210.50x = 1,146,550.89
5. Step 5: Solve for x
   x = 1,146,550.89/1,210.50
6. Step 6: Final answer
   x = 947.17