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Finding the Fourth Proportional to 285.98, 428.88 and 139.64

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Solution

The fourth proportional to 285.98, 428.88 and 139.64 is: 209.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.98 : 428.88 = 139.64 : x
  2. Step 2: Convert to fraction form
    285.98/428.88 = 139.64/x
  3. Step 3: Cross multiply
    285.98x = 428.88 × 139.64
  4. Step 4: Simplify right side
    285.98x = 59,886.66
  5. Step 5: Solve for x
    x = 59,886.66/285.98
  6. Step 6: Final answer
    x = 209.41

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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.