Finding the Fourth Proportional to 1,568.90, 2,164.89 and 905.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,568.90 : 2,164.89 = 905.72 : x
2. Step 2: Convert to fraction form
   1,568.90/2,164.89 = 905.72/x
3. Step 3: Cross multiply
   1,568.90x = 2,164.89 × 905.72
4. Step 4: Simplify right side
   1,568.90x = 1,960,784.17
5. Step 5: Solve for x
   x = 1,960,784.17/1,568.90
6. Step 6: Final answer
   x = 1,249.78