Finding the Fourth Proportional to 1,276.55, 1,761.59 and 780.02

Step by Step Solution

1. Step 1: Write the proportion equation
   1,276.55 : 1,761.59 = 780.02 : x
2. Step 2: Convert to fraction form
   1,276.55/1,761.59 = 780.02/x
3. Step 3: Cross multiply
   1,276.55x = 1,761.59 × 780.02
4. Step 4: Simplify right side
   1,276.55x = 1,374,079.95
5. Step 5: Solve for x
   x = 1,374,079.95/1,276.55
6. Step 6: Final answer
   x = 1,076.40