Finding the Third Proportional to 279.19 and 398.72

Step by Step Solution

1. Step 1: Write the proportion equation
   279.19 : 398.72 = 398.72 : x
2. Step 2: Convert to fraction form
   279.19/398.72 = 398.72/x
3. Step 3: Cross multiply
   279.19x = 398.72 × 398.72
4. Step 4: Simplify right side
   279.19x = 158,976.64
5. Step 5: Solve for x
   x = 158,976.64/279.19
6. Step 6: Final answer
   x = 569.43