Finding the Fourth Proportional to 1,390.38, 1,919.70 and 948.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.38 : 1,919.70 = 948.12 : x
2. Step 2: Convert to fraction form
   1,390.38/1,919.70 = 948.12/x
3. Step 3: Cross multiply
   1,390.38x = 1,919.70 × 948.12
4. Step 4: Simplify right side
   1,390.38x = 1,820,105.96
5. Step 5: Solve for x
   x = 1,820,105.96/1,390.38
6. Step 6: Final answer
   x = 1,309.07