Finding the Fourth Proportional to 91.10, 136.72 and 42.40

Step by Step Solution

1. Step 1: Write the proportion equation
   91.10 : 136.72 = 42.40 : x
2. Step 2: Convert to fraction form
   91.10/136.72 = 42.40/x
3. Step 3: Cross multiply
   91.10x = 136.72 × 42.40
4. Step 4: Simplify right side
   91.10x = 5,796.99
5. Step 5: Solve for x
   x = 5,796.99/91.10
6. Step 6: Final answer
   x = 63.64