Finding the Fourth Proportional to 1,390.27, 1,918.53 and 760.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.27 : 1,918.53 = 760.80 : x
2. Step 2: Convert to fraction form
   1,390.27/1,918.53 = 760.80/x
3. Step 3: Cross multiply
   1,390.27x = 1,918.53 × 760.80
4. Step 4: Simplify right side
   1,390.27x = 1,459,617.62
5. Step 5: Solve for x
   x = 1,459,617.62/1,390.27
6. Step 6: Final answer
   x = 1,049.88