Finding the Fourth Proportional to 1,390.38, 1,916.10 and 996.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.38 : 1,916.10 = 996.72 : x
2. Step 2: Convert to fraction form
   1,390.38/1,916.10 = 996.72/x
3. Step 3: Cross multiply
   1,390.38x = 1,916.10 × 996.72
4. Step 4: Simplify right side
   1,390.38x = 1,909,815.19
5. Step 5: Solve for x
   x = 1,909,815.19/1,390.38
6. Step 6: Final answer
   x = 1,373.59