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Finding the Fourth Proportional to 65.50, 90.40 and 39.64

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Solution

The fourth proportional to 65.50, 90.40 and 39.64 is: 54.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.50 : 90.40 = 39.64 : x
  2. Step 2: Convert to fraction form
    65.50/90.40 = 39.64/x
  3. Step 3: Cross multiply
    65.50x = 90.40 × 39.64
  4. Step 4: Simplify right side
    65.50x = 3,583.46
  5. Step 5: Solve for x
    x = 3,583.46/65.50
  6. Step 6: Final answer
    x = 54.71

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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.