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Finding the Fourth Proportional to 65.69, 90.61 and 39.80

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Solution

The fourth proportional to 65.69, 90.61 and 39.80 is: 54.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.69 : 90.61 = 39.80 : x
  2. Step 2: Convert to fraction form
    65.69/90.61 = 39.80/x
  3. Step 3: Cross multiply
    65.69x = 90.61 × 39.80
  4. Step 4: Simplify right side
    65.69x = 3,606.28
  5. Step 5: Solve for x
    x = 3,606.28/65.69
  6. Step 6: Final answer
    x = 54.90

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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.