Finding the Fourth Proportional to 1,158.55, 1,737.05 and 638.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,158.55 : 1,737.05 = 638.79 : x
2. Step 2: Convert to fraction form
   1,158.55/1,737.05 = 638.79/x
3. Step 3: Cross multiply
   1,158.55x = 1,737.05 × 638.79
4. Step 4: Simplify right side
   1,158.55x = 1,109,606.98
5. Step 5: Solve for x
   x = 1,109,606.98/1,158.55
6. Step 6: Final answer
   x = 957.76