Finding the Fourth Proportional to 1,387.38, 1,911.96 and 993.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.38 : 1,911.96 = 993.72 : x
2. Step 2: Convert to fraction form
   1,387.38/1,911.96 = 993.72/x
3. Step 3: Cross multiply
   1,387.38x = 1,911.96 × 993.72
4. Step 4: Simplify right side
   1,387.38x = 1,899,952.89
5. Step 5: Solve for x
   x = 1,899,952.89/1,387.38
6. Step 6: Final answer
   x = 1,369.45