Finding the Fourth Proportional to 1,398.74, 1,926.92 and 978.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.74 : 1,926.92 = 978.30 : x
2. Step 2: Convert to fraction form
   1,398.74/1,926.92 = 978.30/x
3. Step 3: Cross multiply
   1,398.74x = 1,926.92 × 978.30
4. Step 4: Simplify right side
   1,398.74x = 1,885,105.84
5. Step 5: Solve for x
   x = 1,885,105.84/1,398.74
6. Step 6: Final answer
   x = 1,347.72