Finding the Fourth Proportional to 1,405.72, 1,939.74 and 776.24

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.72 : 1,939.74 = 776.24 : x
2. Step 2: Convert to fraction form
   1,405.72/1,939.74 = 776.24/x
3. Step 3: Cross multiply
   1,405.72x = 1,939.74 × 776.24
4. Step 4: Simplify right side
   1,405.72x = 1,505,703.78
5. Step 5: Solve for x
   x = 1,505,703.78/1,405.72
6. Step 6: Final answer
   x = 1,071.13