Finding the Fourth Proportional to 1,661.72, 2,491.99 and 839.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,661.72 : 2,491.99 = 839.45 : x
2. Step 2: Convert to fraction form
   1,661.72/2,491.99 = 839.45/x
3. Step 3: Cross multiply
   1,661.72x = 2,491.99 × 839.45
4. Step 4: Simplify right side
   1,661.72x = 2,091,905.14
5. Step 5: Solve for x
   x = 2,091,905.14/1,661.72
6. Step 6: Final answer
   x = 1,258.88