Finding the Fourth Proportional to 1,319.56, 1,978.73 and 771.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,319.56 : 1,978.73 = 771.91 : x
2. Step 2: Convert to fraction form
   1,319.56/1,978.73 = 771.91/x
3. Step 3: Cross multiply
   1,319.56x = 1,978.73 × 771.91
4. Step 4: Simplify right side
   1,319.56x = 1,527,401.47
5. Step 5: Solve for x
   x = 1,527,401.47/1,319.56
6. Step 6: Final answer
   x = 1,157.51