Finding the Fourth Proportional to 91.50, 137.20 and 42.75

Step by Step Solution

1. Step 1: Write the proportion equation
   91.50 : 137.20 = 42.75 : x
2. Step 2: Convert to fraction form
   91.50/137.20 = 42.75/x
3. Step 3: Cross multiply
   91.50x = 137.20 × 42.75
4. Step 4: Simplify right side
   91.50x = 5,865.30
5. Step 5: Solve for x
   x = 5,865.30/91.50
6. Step 6: Final answer
   x = 64.10