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Finding the Fourth Proportional to 285.72, 428.64 and 139.58

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Solution

The fourth proportional to 285.72, 428.64 and 139.58 is: 209.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.72 : 428.64 = 139.58 : x
  2. Step 2: Convert to fraction form
    285.72/428.64 = 139.58/x
  3. Step 3: Cross multiply
    285.72x = 428.64 × 139.58
  4. Step 4: Simplify right side
    285.72x = 59,829.57
  5. Step 5: Solve for x
    x = 59,829.57/285.72
  6. Step 6: Final answer
    x = 209.40

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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.