Finding the Fourth Proportional to 1,392.66, 1,920.80 and 972.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.66 : 1,920.80 = 972.89 : x
2. Step 2: Convert to fraction form
   1,392.66/1,920.80 = 972.89/x
3. Step 3: Cross multiply
   1,392.66x = 1,920.80 × 972.89
4. Step 4: Simplify right side
   1,392.66x = 1,868,712.64
5. Step 5: Solve for x
   x = 1,868,712.64/1,392.66
6. Step 6: Final answer
   x = 1,341.83