Finding the Fourth Proportional to 1,386.65, 1,913.81 and 938.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.65 : 1,913.81 = 938.31 : x
2. Step 2: Convert to fraction form
   1,386.65/1,913.81 = 938.31/x
3. Step 3: Cross multiply
   1,386.65x = 1,913.81 × 938.31
4. Step 4: Simplify right side
   1,386.65x = 1,795,742.37
5. Step 5: Solve for x
   x = 1,795,742.37/1,386.65
6. Step 6: Final answer
   x = 1,295.03