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Finding the Fourth Proportional to 65.75, 90.75 and 39.89

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Solution

The fourth proportional to 65.75, 90.75 and 39.89 is: 55.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.75 : 90.75 = 39.89 : x
  2. Step 2: Convert to fraction form
    65.75/90.75 = 39.89/x
  3. Step 3: Cross multiply
    65.75x = 90.75 × 39.89
  4. Step 4: Simplify right side
    65.75x = 3,620.02
  5. Step 5: Solve for x
    x = 3,620.02/65.75
  6. Step 6: Final answer
    x = 55.06

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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.