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Finding the Fourth Proportional to 1,223.68, 1,687.60 and 831.20

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Solution

The fourth proportional to 1,223.68, 1,687.60 and 831.20 is: 1,146.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,223.68 : 1,687.60 = 831.20 : x
  2. Step 2: Convert to fraction form
    1,223.68/1,687.60 = 831.20/x
  3. Step 3: Cross multiply
    1,223.68x = 1,687.60 × 831.20
  4. Step 4: Simplify right side
    1,223.68x = 1,402,733.12
  5. Step 5: Solve for x
    x = 1,402,733.12/1,223.68
  6. Step 6: Final answer
    x = 1,146.32

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.