Finding the Fourth Proportional to 1,405.56, 1,939.50 and 939

Step by Step Solution

1. Step 1: Write the proportion equation
   1,405.56 : 1,939.50 = 939 : x
2. Step 2: Convert to fraction form
   1,405.56/1,939.50 = 939/x
3. Step 3: Cross multiply
   1,405.56x = 1,939.50 × 939
4. Step 4: Simplify right side
   1,405.56x = 1,821,190.50
5. Step 5: Solve for x
   x = 1,821,190.50/1,405.56
6. Step 6: Final answer
   x = 1,295.70