Finding the Fourth Proportional to 1,641.72, 2,265.89 and 978.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.72 : 2,265.89 = 978.96 : x
2. Step 2: Convert to fraction form
   1,641.72/2,265.89 = 978.96/x
3. Step 3: Cross multiply
   1,641.72x = 2,265.89 × 978.96
4. Step 4: Simplify right side
   1,641.72x = 2,218,215.67
5. Step 5: Solve for x
   x = 2,218,215.67/1,641.72
6. Step 6: Final answer
   x = 1,351.15