Finding the Fourth Proportional to 105.51, 145.61 and 61.86

Step by Step Solution

1. Step 1: Write the proportion equation
   105.51 : 145.61 = 61.86 : x
2. Step 2: Convert to fraction form
   105.51/145.61 = 61.86/x
3. Step 3: Cross multiply
   105.51x = 145.61 × 61.86
4. Step 4: Simplify right side
   105.51x = 9,007.43
5. Step 5: Solve for x
   x = 9,007.43/105.51
6. Step 6: Final answer
   x = 85.37