Finding the Fourth Proportional to 1,389.78, 1,914.91 and 996.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.78 : 1,914.91 = 996.12 : x
2. Step 2: Convert to fraction form
   1,389.78/1,914.91 = 996.12/x
3. Step 3: Cross multiply
   1,389.78x = 1,914.91 × 996.12
4. Step 4: Simplify right side
   1,389.78x = 1,907,477.66
5. Step 5: Solve for x
   x = 1,907,477.66/1,389.78
6. Step 6: Final answer
   x = 1,372.50