Finding the Fourth Proportional to 83.89, 125.77 and 42.78

Step by Step Solution

1. Step 1: Write the proportion equation
   83.89 : 125.77 = 42.78 : x
2. Step 2: Convert to fraction form
   83.89/125.77 = 42.78/x
3. Step 3: Cross multiply
   83.89x = 125.77 × 42.78
4. Step 4: Simplify right side
   83.89x = 5,380.44
5. Step 5: Solve for x
   x = 5,380.44/83.89
6. Step 6: Final answer
   x = 64.14