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Finding the Fourth Proportional to 55.72, 76.86 and 39.40

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Solution

The fourth proportional to 55.72, 76.86 and 39.40 is: 54.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    55.72 : 76.86 = 39.40 : x
  2. Step 2: Convert to fraction form
    55.72/76.86 = 39.40/x
  3. Step 3: Cross multiply
    55.72x = 76.86 × 39.40
  4. Step 4: Simplify right side
    55.72x = 3,028.28
  5. Step 5: Solve for x
    x = 3,028.28/55.72
  6. Step 6: Final answer
    x = 54.35

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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.