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Finding the Fourth Proportional to 781.21, 1,171.44 and 287.28

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Solution

The fourth proportional to 781.21, 1,171.44 and 287.28 is: 430.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.21 : 1,171.44 = 287.28 : x
  2. Step 2: Convert to fraction form
    781.21/1,171.44 = 287.28/x
  3. Step 3: Cross multiply
    781.21x = 1,171.44 × 287.28
  4. Step 4: Simplify right side
    781.21x = 336,531.28
  5. Step 5: Solve for x
    x = 336,531.28/781.21
  6. Step 6: Final answer
    x = 430.78

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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.