Finding the Fourth Proportional to 15.98, 21.94 and 15.42

Step by Step Solution

1. Step 1: Write the proportion equation
   15.98 : 21.94 = 15.42 : x
2. Step 2: Convert to fraction form
   15.98/21.94 = 15.42/x
3. Step 3: Cross multiply
   15.98x = 21.94 × 15.42
4. Step 4: Simplify right side
   15.98x = 338.31
5. Step 5: Solve for x
   x = 338.31/15.98
6. Step 6: Final answer
   x = 21.17