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Finding the Fourth Proportional to 1,319.60, 1,978.32 and 831.44

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Solution

The fourth proportional to 1,319.60, 1,978.32 and 831.44 is: 1,246.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.60 : 1,978.32 = 831.44 : x
  2. Step 2: Convert to fraction form
    1,319.60/1,978.32 = 831.44/x
  3. Step 3: Cross multiply
    1,319.60x = 1,978.32 × 831.44
  4. Step 4: Simplify right side
    1,319.60x = 1,644,854.38
  5. Step 5: Solve for x
    x = 1,644,854.38/1,319.60
  6. Step 6: Final answer
    x = 1,246.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.