Finding the Fourth Proportional to 1,390.05, 1,918.24 and 830.49

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.05 : 1,918.24 = 830.49 : x
2. Step 2: Convert to fraction form
   1,390.05/1,918.24 = 830.49/x
3. Step 3: Cross multiply
   1,390.05x = 1,918.24 × 830.49
4. Step 4: Simplify right side
   1,390.05x = 1,593,079.14
5. Step 5: Solve for x
   x = 1,593,079.14/1,390.05
6. Step 6: Final answer
   x = 1,146.06