Finding the Fourth Proportional to 53.91, 80.78 and 42.53

Step by Step Solution

1. Step 1: Write the proportion equation
   53.91 : 80.78 = 42.53 : x
2. Step 2: Convert to fraction form
   53.91/80.78 = 42.53/x
3. Step 3: Cross multiply
   53.91x = 80.78 × 42.53
4. Step 4: Simplify right side
   53.91x = 3,434.96
5. Step 5: Solve for x
   x = 3,434.96/53.91
6. Step 6: Final answer
   x = 63.72