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Finding the Fourth Proportional to 61.81, 85.28 and 42.15

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Solution

The fourth proportional to 61.81, 85.28 and 42.15 is: 58.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    61.81 : 85.28 = 42.15 : x
  2. Step 2: Convert to fraction form
    61.81/85.28 = 42.15/x
  3. Step 3: Cross multiply
    61.81x = 85.28 × 42.15
  4. Step 4: Simplify right side
    61.81x = 3,594.55
  5. Step 5: Solve for x
    x = 3,594.55/61.81
  6. Step 6: Final answer
    x = 58.16

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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.