Finding the Fourth Proportional to 3,587.78, 5,381.98 and 990.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,587.78 : 5,381.98 = 990.72 : x
2. Step 2: Convert to fraction form
   3,587.78/5,381.98 = 990.72/x
3. Step 3: Cross multiply
   3,587.78x = 5,381.98 × 990.72
4. Step 4: Simplify right side
   3,587.78x = 5,332,035.23
5. Step 5: Solve for x
   x = 5,332,035.23/3,587.78
6. Step 6: Final answer
   x = 1,486.17