Finding the Fourth Proportional to 1,390.34, 1,917.76 and 830.38

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.34 : 1,917.76 = 830.38 : x
2. Step 2: Convert to fraction form
   1,390.34/1,917.76 = 830.38/x
3. Step 3: Cross multiply
   1,390.34x = 1,917.76 × 830.38
4. Step 4: Simplify right side
   1,390.34x = 1,592,459.96
5. Step 5: Solve for x
   x = 1,592,459.96/1,390.34
6. Step 6: Final answer
   x = 1,145.37