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Finding the Fourth Proportional to 285.12, 427.60 and 138.72

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Solution

The fourth proportional to 285.12, 427.60 and 138.72 is: 208.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.12 : 427.60 = 138.72 : x
  2. Step 2: Convert to fraction form
    285.12/427.60 = 138.72/x
  3. Step 3: Cross multiply
    285.12x = 427.60 × 138.72
  4. Step 4: Simplify right side
    285.12x = 59,316.67
  5. Step 5: Solve for x
    x = 59,316.67/285.12
  6. Step 6: Final answer
    x = 208.04

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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.