Finding the Fourth Proportional to 1,780.40, 2,457.20 and 994.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,780.40 : 2,457.20 = 994.50 : x
2. Step 2: Convert to fraction form
   1,780.40/2,457.20 = 994.50/x
3. Step 3: Cross multiply
   1,780.40x = 2,457.20 × 994.50
4. Step 4: Simplify right side
   1,780.40x = 2,443,687.89
5. Step 5: Solve for x
   x = 2,443,687.89/1,780.40
6. Step 6: Final answer
   x = 1,372.55