Finding the Fourth Proportional to 1,361.91, 1,879.70 and 772.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,361.91 : 1,879.70 = 772.50 : x
2. Step 2: Convert to fraction form
   1,361.91/1,879.70 = 772.50/x
3. Step 3: Cross multiply
   1,361.91x = 1,879.70 × 772.50
4. Step 4: Simplify right side
   1,361.91x = 1,452,064.39
5. Step 5: Solve for x
   x = 1,452,064.39/1,361.91
6. Step 6: Final answer
   x = 1,066.20