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Finding the Fourth Proportional to 64.80, 89.40 and 38.88

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Solution

The fourth proportional to 64.80, 89.40 and 38.88 is: 53.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.80 : 89.40 = 38.88 : x
  2. Step 2: Convert to fraction form
    64.80/89.40 = 38.88/x
  3. Step 3: Cross multiply
    64.80x = 89.40 × 38.88
  4. Step 4: Simplify right side
    64.80x = 3,475.87
  5. Step 5: Solve for x
    x = 3,475.87/64.80
  6. Step 6: Final answer
    x = 53.64

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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.