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Finding the Fourth Proportional to 65.72, 90.72 and 51.20

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Solution

The fourth proportional to 65.72, 90.72 and 51.20 is: 70.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.72 : 90.72 = 51.20 : x
  2. Step 2: Convert to fraction form
    65.72/90.72 = 51.20/x
  3. Step 3: Cross multiply
    65.72x = 90.72 × 51.20
  4. Step 4: Simplify right side
    65.72x = 4,644.86
  5. Step 5: Solve for x
    x = 4,644.86/65.72
  6. Step 6: Final answer
    x = 70.68

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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.