Finding the Fourth Proportional to 1,641.80, 2,265.74 and 978.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.80 : 2,265.74 = 978.72 : x
2. Step 2: Convert to fraction form
   1,641.80/2,265.74 = 978.72/x
3. Step 3: Cross multiply
   1,641.80x = 2,265.74 × 978.72
4. Step 4: Simplify right side
   1,641.80x = 2,217,525.05
5. Step 5: Solve for x
   x = 2,217,525.05/1,641.80
6. Step 6: Final answer
   x = 1,350.67