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Finding the Fourth Proportional to 63.72, 87.90 and 51.40

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Solution

The fourth proportional to 63.72, 87.90 and 51.40 is: 70.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    63.72 : 87.90 = 51.40 : x
  2. Step 2: Convert to fraction form
    63.72/87.90 = 51.40/x
  3. Step 3: Cross multiply
    63.72x = 87.90 × 51.40
  4. Step 4: Simplify right side
    63.72x = 4,518.06
  5. Step 5: Solve for x
    x = 4,518.06/63.72
  6. Step 6: Final answer
    x = 70.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.