Finding the Fourth Proportional to 1,386.81, 1,912.88 and 1,008.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.81 : 1,912.88 = 1,008.07 : x
2. Step 2: Convert to fraction form
   1,386.81/1,912.88 = 1,008.07/x
3. Step 3: Cross multiply
   1,386.81x = 1,912.88 × 1,008.07
4. Step 4: Simplify right side
   1,386.81x = 1,928,302.34
5. Step 5: Solve for x
   x = 1,928,302.34/1,386.81
6. Step 6: Final answer
   x = 1,390.46