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Finding the Fourth Proportional to 285.90, 428.88 and 90.91

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Solution

The fourth proportional to 285.90, 428.88 and 90.91 is: 136.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.90 : 428.88 = 90.91 : x
  2. Step 2: Convert to fraction form
    285.90/428.88 = 90.91/x
  3. Step 3: Cross multiply
    285.90x = 428.88 × 90.91
  4. Step 4: Simplify right side
    285.90x = 38,989.48
  5. Step 5: Solve for x
    x = 38,989.48/285.90
  6. Step 6: Final answer
    x = 136.37

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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.