Finding the Fourth Proportional to 1,642.18, 2,265.94 and 978.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,642.18 : 2,265.94 = 978.79 : x
2. Step 2: Convert to fraction form
   1,642.18/2,265.94 = 978.79/x
3. Step 3: Cross multiply
   1,642.18x = 2,265.94 × 978.79
4. Step 4: Simplify right side
   1,642.18x = 2,217,874.52
5. Step 5: Solve for x
   x = 2,217,874.52/1,642.18
6. Step 6: Final answer
   x = 1,350.57