Finding the Fourth Proportional to 1,405.21, 1,939.18 and 775.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.21 : 1,939.18 = 775.74 : x
2. Step 2: Convert to fraction form
   1,405.21/1,939.18 = 775.74/x
3. Step 3: Cross multiply
   1,405.21x = 1,939.18 × 775.74
4. Step 4: Simplify right side
   1,405.21x = 1,504,301.92
5. Step 5: Solve for x
   x = 1,504,301.92/1,405.21
6. Step 6: Final answer
   x = 1,070.52