Finding the Fourth Proportional to 123.90, 185.86 and 42.72

Step by Step Solution

1. Step 1: Write the proportion equation
   123.90 : 185.86 = 42.72 : x
2. Step 2: Convert to fraction form
   123.90/185.86 = 42.72/x
3. Step 3: Cross multiply
   123.90x = 185.86 × 42.72
4. Step 4: Simplify right side
   123.90x = 7,940.34
5. Step 5: Solve for x
   x = 7,940.34/123.90
6. Step 6: Final answer
   x = 64.09