Finding the Fourth Proportional to 1,210.72, 1,670.61 and 686.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,210.72 : 1,670.61 = 686.56 : x
2. Step 2: Convert to fraction form
   1,210.72/1,670.61 = 686.56/x
3. Step 3: Cross multiply
   1,210.72x = 1,670.61 × 686.56
4. Step 4: Simplify right side
   1,210.72x = 1,146,974.00
5. Step 5: Solve for x
   x = 1,146,974.00/1,210.72
6. Step 6: Final answer
   x = 947.35