Finding the Fourth Proportional to 61.42, 91.72 and 55.30

Step by Step Solution

1. Step 1: Write the proportion equation
   61.42 : 91.72 = 55.30 : x
2. Step 2: Convert to fraction form
   61.42/91.72 = 55.30/x
3. Step 3: Cross multiply
   61.42x = 91.72 × 55.30
4. Step 4: Simplify right side
   61.42x = 5,072.12
5. Step 5: Solve for x
   x = 5,072.12/61.42
6. Step 6: Final answer
   x = 82.58