Finding the Fourth Proportional to 1,015.56, 1,401.06 and 666.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,015.56 : 1,401.06 = 666.42 : x
2. Step 2: Convert to fraction form
   1,015.56/1,401.06 = 666.42/x
3. Step 3: Cross multiply
   1,015.56x = 1,401.06 × 666.42
4. Step 4: Simplify right side
   1,015.56x = 933,694.41
5. Step 5: Solve for x
   x = 933,694.41/1,015.56
6. Step 6: Final answer
   x = 919.39