Finding the Fourth Proportional to 78.50, 108.32 and 71.61

Step by Step Solution

1. Step 1: Write the proportion equation
   78.50 : 108.32 = 71.61 : x
2. Step 2: Convert to fraction form
   78.50/108.32 = 71.61/x
3. Step 3: Cross multiply
   78.50x = 108.32 × 71.61
4. Step 4: Simplify right side
   78.50x = 7,756.80
5. Step 5: Solve for x
   x = 7,756.80/78.50
6. Step 6: Final answer
   x = 98.81