Finding the Fourth Proportional to 71.79, 107.61 and 42.91

Step by Step Solution

1. Step 1: Write the proportion equation
   71.79 : 107.61 = 42.91 : x
2. Step 2: Convert to fraction form
   71.79/107.61 = 42.91/x
3. Step 3: Cross multiply
   71.79x = 107.61 × 42.91
4. Step 4: Simplify right side
   71.79x = 4,617.12
5. Step 5: Solve for x
   x = 4,617.12/71.79
6. Step 6: Final answer
   x = 64.32