Finding the Fourth Proportional to 1,393.67, 2,087.80 and 775.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,393.67 : 2,087.80 = 775.50 : x
2. Step 2: Convert to fraction form
   1,393.67/2,087.80 = 775.50/x
3. Step 3: Cross multiply
   1,393.67x = 2,087.80 × 775.50
4. Step 4: Simplify right side
   1,393.67x = 1,619,086.96
5. Step 5: Solve for x
   x = 1,619,086.96/1,393.67
6. Step 6: Final answer
   x = 1,161.74