Finding the Fourth Proportional to 1,457.12, 2,007.78 and 990.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,457.12 : 2,007.78 = 990.56 : x
2. Step 2: Convert to fraction form
   1,457.12/2,007.78 = 990.56/x
3. Step 3: Cross multiply
   1,457.12x = 2,007.78 × 990.56
4. Step 4: Simplify right side
   1,457.12x = 1,988,826.56
5. Step 5: Solve for x
   x = 1,988,826.56/1,457.12
6. Step 6: Final answer
   x = 1,364.90