Finding the Third Proportional to 42.09 and 61.78

Step by Step Solution

1. Step 1: Write the proportion equation
   42.09 : 61.78 = 61.78 : x
2. Step 2: Convert to fraction form
   42.09/61.78 = 61.78/x
3. Step 3: Cross multiply
   42.09x = 61.78 × 61.78
4. Step 4: Simplify right side
   42.09x = 3,816.92
5. Step 5: Solve for x
   x = 3,816.92/42.09
6. Step 6: Final answer
   x = 90.68