Finding the Fourth Proportional to 78.21, 107.89 and 53.61

Step by Step Solution

1. Step 1: Write the proportion equation
   78.21 : 107.89 = 53.61 : x
2. Step 2: Convert to fraction form
   78.21/107.89 = 53.61/x
3. Step 3: Cross multiply
   78.21x = 107.89 × 53.61
4. Step 4: Simplify right side
   78.21x = 5,783.98
5. Step 5: Solve for x
   x = 5,783.98/78.21
6. Step 6: Final answer
   x = 73.95