Finding the Fourth Proportional to 1,018.71, 1,406.61 and 664.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.71 : 1,406.61 = 664.74 : x
2. Step 2: Convert to fraction form
   1,018.71/1,406.61 = 664.74/x
3. Step 3: Cross multiply
   1,018.71x = 1,406.61 × 664.74
4. Step 4: Simplify right side
   1,018.71x = 935,029.93
5. Step 5: Solve for x
   x = 935,029.93/1,018.71
6. Step 6: Final answer
   x = 917.86