Finding the Fourth Proportional to 1,311.42, 1,962.72 and 762.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,311.42 : 1,962.72 = 762.78 : x
2. Step 2: Convert to fraction form
   1,311.42/1,962.72 = 762.78/x
3. Step 3: Cross multiply
   1,311.42x = 1,962.72 × 762.78
4. Step 4: Simplify right side
   1,311.42x = 1,497,123.56
5. Step 5: Solve for x
   x = 1,497,123.56/1,311.42
6. Step 6: Final answer
   x = 1,141.60