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Finding the Fourth Proportional to 287.90, 431.84 and 71.47

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Solution

The fourth proportional to 287.90, 431.84 and 71.47 is: 107.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.90 : 431.84 = 71.47 : x
  2. Step 2: Convert to fraction form
    287.90/431.84 = 71.47/x
  3. Step 3: Cross multiply
    287.90x = 431.84 × 71.47
  4. Step 4: Simplify right side
    287.90x = 30,865.54
  5. Step 5: Solve for x
    x = 30,865.54/287.90
  6. Step 6: Final answer
    x = 107.21

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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.