Finding the Fourth Proportional to 1,039.34, 1,436.20 and 988.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,039.34 : 1,436.20 = 988.72 : x
2. Step 2: Convert to fraction form
   1,039.34/1,436.20 = 988.72/x
3. Step 3: Cross multiply
   1,039.34x = 1,436.20 × 988.72
4. Step 4: Simplify right side
   1,039.34x = 1,419,999.66
5. Step 5: Solve for x
   x = 1,419,999.66/1,039.34
6. Step 6: Final answer
   x = 1,366.25