Finding the Fourth Proportional to 1,428.06, 1,971.50 and 931

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.06 : 1,971.50 = 931 : x
2. Step 2: Convert to fraction form
   1,428.06/1,971.50 = 931/x
3. Step 3: Cross multiply
   1,428.06x = 1,971.50 × 931
4. Step 4: Simplify right side
   1,428.06x = 1,835,466.50
5. Step 5: Solve for x
   x = 1,835,466.50/1,428.06
6. Step 6: Final answer
   x = 1,285.29