Finding the Fourth Proportional to 2,085.21, 3,127.91 and 786.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,085.21 : 3,127.91 = 786.78 : x
2. Step 2: Convert to fraction form
   2,085.21/3,127.91 = 786.78/x
3. Step 3: Cross multiply
   2,085.21x = 3,127.91 × 786.78
4. Step 4: Simplify right side
   2,085.21x = 2,460,973.10
5. Step 5: Solve for x
   x = 2,460,973.10/2,085.21
6. Step 6: Final answer
   x = 1,180.20