Finding the Fourth Proportional to 1,390.62, 1,918.38 and 830.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.62 : 1,918.38 = 830.76 : x
2. Step 2: Convert to fraction form
   1,390.62/1,918.38 = 830.76/x
3. Step 3: Cross multiply
   1,390.62x = 1,918.38 × 830.76
4. Step 4: Simplify right side
   1,390.62x = 1,593,713.37
5. Step 5: Solve for x
   x = 1,593,713.37/1,390.62
6. Step 6: Final answer
   x = 1,146.05