Finding the Fourth Proportional to 1,015.79, 1,521.56 and 648.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,015.79 : 1,521.56 = 648.71 : x
2. Step 2: Convert to fraction form
   1,015.79/1,521.56 = 648.71/x
3. Step 3: Cross multiply
   1,015.79x = 1,521.56 × 648.71
4. Step 4: Simplify right side
   1,015.79x = 987,045.76
5. Step 5: Solve for x
   x = 987,045.76/1,015.79
6. Step 6: Final answer
   x = 971.70