Finding the Fourth Proportional to 1,390.46, 1,917.99 and 918.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.46 : 1,917.99 = 918.18 : x
2. Step 2: Convert to fraction form
   1,390.46/1,917.99 = 918.18/x
3. Step 3: Cross multiply
   1,390.46x = 1,917.99 × 918.18
4. Step 4: Simplify right side
   1,390.46x = 1,761,060.06
5. Step 5: Solve for x
   x = 1,761,060.06/1,390.46
6. Step 6: Final answer
   x = 1,266.53