Finding the Fourth Proportional to 78.45, 108.24 and 53.91

Step by Step Solution

1. Step 1: Write the proportion equation
   78.45 : 108.24 = 53.91 : x
2. Step 2: Convert to fraction form
   78.45/108.24 = 53.91/x
3. Step 3: Cross multiply
   78.45x = 108.24 × 53.91
4. Step 4: Simplify right side
   78.45x = 5,835.22
5. Step 5: Solve for x
   x = 5,835.22/78.45
6. Step 6: Final answer
   x = 74.38