Finding the Fourth Proportional to 83.42, 125.15 and 42.90

Step by Step Solution

1. Step 1: Write the proportion equation
   83.42 : 125.15 = 42.90 : x
2. Step 2: Convert to fraction form
   83.42/125.15 = 42.90/x
3. Step 3: Cross multiply
   83.42x = 125.15 × 42.90
4. Step 4: Simplify right side
   83.42x = 5,368.94
5. Step 5: Solve for x
   x = 5,368.94/83.42
6. Step 6: Final answer
   x = 64.36