Finding the Fourth Proportional to 1,390.91, 1,919.47 and 761.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.91 : 1,919.47 = 761.42 : x
2. Step 2: Convert to fraction form
   1,390.91/1,919.47 = 761.42/x
3. Step 3: Cross multiply
   1,390.91x = 1,919.47 × 761.42
4. Step 4: Simplify right side
   1,390.91x = 1,461,531.46
5. Step 5: Solve for x
   x = 1,461,531.46/1,390.91
6. Step 6: Final answer
   x = 1,050.78