Finding the Fourth Proportional to 1,210.52, 1,670.50 and 686.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,210.52 : 1,670.50 = 686.55 : x
2. Step 2: Convert to fraction form
   1,210.52/1,670.50 = 686.55/x
3. Step 3: Cross multiply
   1,210.52x = 1,670.50 × 686.55
4. Step 4: Simplify right side
   1,210.52x = 1,146,881.78
5. Step 5: Solve for x
   x = 1,146,881.78/1,210.52
6. Step 6: Final answer
   x = 947.43