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Finding the Fourth Proportional to 64.61, 89.15 and 39.70

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Solution

The fourth proportional to 64.61, 89.15 and 39.70 is: 54.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.61 : 89.15 = 39.70 : x
  2. Step 2: Convert to fraction form
    64.61/89.15 = 39.70/x
  3. Step 3: Cross multiply
    64.61x = 89.15 × 39.70
  4. Step 4: Simplify right side
    64.61x = 3,539.26
  5. Step 5: Solve for x
    x = 3,539.26/64.61
  6. Step 6: Final answer
    x = 54.78

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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.