Finding the Fourth Proportional to 1,213.79, 1,674.87 and 689.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,213.79 : 1,674.87 = 689.72 : x
2. Step 2: Convert to fraction form
   1,213.79/1,674.87 = 689.72/x
3. Step 3: Cross multiply
   1,213.79x = 1,674.87 × 689.72
4. Step 4: Simplify right side
   1,213.79x = 1,155,191.34
5. Step 5: Solve for x
   x = 1,155,191.34/1,213.79
6. Step 6: Final answer
   x = 951.72