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Finding the Fourth Proportional to 42.90, 59.31 and 39.21

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Solution

The fourth proportional to 42.90, 59.31 and 39.21 is: 54.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.90 : 59.31 = 39.21 : x
  2. Step 2: Convert to fraction form
    42.90/59.31 = 39.21/x
  3. Step 3: Cross multiply
    42.90x = 59.31 × 39.21
  4. Step 4: Simplify right side
    42.90x = 2,325.55
  5. Step 5: Solve for x
    x = 2,325.55/42.90
  6. Step 6: Final answer
    x = 54.21

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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.