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Finding the Fourth Proportional to 76.20, 105 and 64.50

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Solution

The fourth proportional to 76.20, 105 and 64.50 is: 88.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.20 : 105 = 64.50 : x
  2. Step 2: Convert to fraction form
    76.20/105 = 64.50/x
  3. Step 3: Cross multiply
    76.20x = 105 × 64.50
  4. Step 4: Simplify right side
    76.20x = 6,772.50
  5. Step 5: Solve for x
    x = 6,772.50/76.20
  6. Step 6: Final answer
    x = 88.88

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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.