Finding the Fourth Proportional to 1,978.42, 2,731.08 and 1,391.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,978.42 : 2,731.08 = 1,391.14 : x
2. Step 2: Convert to fraction form
   1,978.42/2,731.08 = 1,391.14/x
3. Step 3: Cross multiply
   1,978.42x = 2,731.08 × 1,391.14
4. Step 4: Simplify right side
   1,978.42x = 3,799,314.63
5. Step 5: Solve for x
   x = 3,799,314.63/1,978.42
6. Step 6: Final answer
   x = 1,920.38