Finding the Fourth Proportional to 1,054.72, 1,581.42 and 405.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,054.72 : 1,581.42 = 405.30 : x
2. Step 2: Convert to fraction form
   1,054.72/1,581.42 = 405.30/x
3. Step 3: Cross multiply
   1,054.72x = 1,581.42 × 405.30
4. Step 4: Simplify right side
   1,054.72x = 640,956.98
5. Step 5: Solve for x
   x = 640,956.98/1,054.72
6. Step 6: Final answer
   x = 607.70