Finding the Fourth Proportional to 1,320.10, 1,978.88 and 772.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,320.10 : 1,978.88 = 772.18 : x
2. Step 2: Convert to fraction form
   1,320.10/1,978.88 = 772.18/x
3. Step 3: Cross multiply
   1,320.10x = 1,978.88 × 772.18
4. Step 4: Simplify right side
   1,320.10x = 1,528,051.56
5. Step 5: Solve for x
   x = 1,528,051.56/1,320.10
6. Step 6: Final answer
   x = 1,157.53