Finding the Fourth Proportional to 1,428.51, 1,970.66 and 931.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.51 : 1,970.66 = 931.31 : x
2. Step 2: Convert to fraction form
   1,428.51/1,970.66 = 931.31/x
3. Step 3: Cross multiply
   1,428.51x = 1,970.66 × 931.31
4. Step 4: Simplify right side
   1,428.51x = 1,835,287.84
5. Step 5: Solve for x
   x = 1,835,287.84/1,428.51
6. Step 6: Final answer
   x = 1,284.76