Finding the Fourth Proportional to 82.71, 123.75 and 42

Step by Step Solution

1. Step 1: Write the proportion equation
   82.71 : 123.75 = 42 : x
2. Step 2: Convert to fraction form
   82.71/123.75 = 42/x
3. Step 3: Cross multiply
   82.71x = 123.75 × 42
4. Step 4: Simplify right side
   82.71x = 5,197.50
5. Step 5: Solve for x
   x = 5,197.50/82.71
6. Step 6: Final answer
   x = 62.84