Finding the Fourth Proportional to 1,641.86, 2,265.86 and 978.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.86 : 2,265.86 = 978.74 : x
2. Step 2: Convert to fraction form
   1,641.86/2,265.86 = 978.74/x
3. Step 3: Cross multiply
   1,641.86x = 2,265.86 × 978.74
4. Step 4: Simplify right side
   1,641.86x = 2,217,687.82
5. Step 5: Solve for x
   x = 2,217,687.82/1,641.86
6. Step 6: Final answer
   x = 1,350.72