Finding the Fourth Proportional to 115.15, 172.72 and 42.00

Step by Step Solution

1. Step 1: Write the proportion equation
   115.15 : 172.72 = 42.00 : x
2. Step 2: Convert to fraction form
   115.15/172.72 = 42.00/x
3. Step 3: Cross multiply
   115.15x = 172.72 × 42.00
4. Step 4: Simplify right side
   115.15x = 7,253.17
5. Step 5: Solve for x
   x = 7,253.17/115.15
6. Step 6: Final answer
   x = 62.99