Finding the Fourth Proportional to 1,386.95, 1,915.31 and 1,189.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.95 : 1,915.31 = 1,189.31 : x
2. Step 2: Convert to fraction form
   1,386.95/1,915.31 = 1,189.31/x
3. Step 3: Cross multiply
   1,386.95x = 1,915.31 × 1,189.31
4. Step 4: Simplify right side
   1,386.95x = 2,277,890.73
5. Step 5: Solve for x
   x = 2,277,890.73/1,386.95
6. Step 6: Final answer
   x = 1,642.38