Finding the Fourth Proportional to 1,258.71, 1,736.42 and 978.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,258.71 : 1,736.42 = 978.45 : x
2. Step 2: Convert to fraction form
   1,258.71/1,736.42 = 978.45/x
3. Step 3: Cross multiply
   1,258.71x = 1,736.42 × 978.45
4. Step 4: Simplify right side
   1,258.71x = 1,698,995.26
5. Step 5: Solve for x
   x = 1,698,995.26/1,258.71
6. Step 6: Final answer
   x = 1,349.79