Finding the Fourth Proportional to 78.00, 107.56 and 51.40

Step by Step Solution

1. Step 1: Write the proportion equation
   78.00 : 107.56 = 51.40 : x
2. Step 2: Convert to fraction form
   78.00/107.56 = 51.40/x
3. Step 3: Cross multiply
   78.00x = 107.56 × 51.40
4. Step 4: Simplify right side
   78.00x = 5,528.78
5. Step 5: Solve for x
   x = 5,528.78/78.00
6. Step 6: Final answer
   x = 70.89