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Finding the Fourth Proportional to 64.20, 88.60 and 39.28

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Solution

The fourth proportional to 64.20, 88.60 and 39.28 is: 54.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.20 : 88.60 = 39.28 : x
  2. Step 2: Convert to fraction form
    64.20/88.60 = 39.28/x
  3. Step 3: Cross multiply
    64.20x = 88.60 × 39.28
  4. Step 4: Simplify right side
    64.20x = 3,480.21
  5. Step 5: Solve for x
    x = 3,480.21/64.20
  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.