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Finding the Fourth Proportional to 61.21, 84.40 and 55.45

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Solution

The fourth proportional to 61.21, 84.40 and 55.45 is: 76.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.21 : 84.40 = 55.45 : x
  2. Step 2: Convert to fraction form
    61.21/84.40 = 55.45/x
  3. Step 3: Cross multiply
    61.21x = 84.40 × 55.45
  4. Step 4: Simplify right side
    61.21x = 4,679.98
  5. Step 5: Solve for x
    x = 4,679.98/61.21
  6. Step 6: Final answer
    x = 76.46

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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.