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Finding the Fourth Proportional to 781.28, 1,172.34 and 319.28

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Solution

The fourth proportional to 781.28, 1,172.34 and 319.28 is: 479.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.28 : 1,172.34 = 319.28 : x
  2. Step 2: Convert to fraction form
    781.28/1,172.34 = 319.28/x
  3. Step 3: Cross multiply
    781.28x = 1,172.34 × 319.28
  4. Step 4: Simplify right side
    781.28x = 374,304.72
  5. Step 5: Solve for x
    x = 374,304.72/781.28
  6. Step 6: Final answer
    x = 479.09

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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.