Finding the Fourth Proportional to 1,389.64, 1,917.78 and 923.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.64 : 1,917.78 = 923.56 : x
2. Step 2: Convert to fraction form
   1,389.64/1,917.78 = 923.56/x
3. Step 3: Cross multiply
   1,389.64x = 1,917.78 × 923.56
4. Step 4: Simplify right side
   1,389.64x = 1,771,184.90
5. Step 5: Solve for x
   x = 1,771,184.90/1,389.64
6. Step 6: Final answer
   x = 1,274.56