Finding the Fourth Proportional to 1,405.80, 1,938.78 and 1,007.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.80 : 1,938.78 = 1,007.82 : x
2. Step 2: Convert to fraction form
   1,405.80/1,938.78 = 1,007.82/x
3. Step 3: Cross multiply
   1,405.80x = 1,938.78 × 1,007.82
4. Step 4: Simplify right side
   1,405.80x = 1,953,941.26
5. Step 5: Solve for x
   x = 1,953,941.26/1,405.80
6. Step 6: Final answer
   x = 1,389.91