Finding the Fourth Proportional to 12,978.51, 17,910.70 and 7,942.64

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.51 : 17,910.70 = 7,942.64 : x
2. Step 2: Convert to fraction form
   12,978.51/17,910.70 = 7,942.64/x
3. Step 3: Cross multiply
   12,978.51x = 17,910.70 × 7,942.64
4. Step 4: Simplify right side
   12,978.51x = 142,258,278.26
5. Step 5: Solve for x
   x = 142,258,278.26/12,978.51
6. Step 6: Final answer
   x = 10,961.06