Finding the Fourth Proportional to 91.61, 137.39 and 53.05

Step by Step Solution

1. Step 1: Write the proportion equation
   91.61 : 137.39 = 53.05 : x
2. Step 2: Convert to fraction form
   91.61/137.39 = 53.05/x
3. Step 3: Cross multiply
   91.61x = 137.39 × 53.05
4. Step 4: Simplify right side
   91.61x = 7,288.54
5. Step 5: Solve for x
   x = 7,288.54/91.61
6. Step 6: Final answer
   x = 79.56