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Finding the Fourth Proportional to 64.65, 89.10 and 57.21

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Solution

The fourth proportional to 64.65, 89.10 and 57.21 is: 78.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.65 : 89.10 = 57.21 : x
  2. Step 2: Convert to fraction form
    64.65/89.10 = 57.21/x
  3. Step 3: Cross multiply
    64.65x = 89.10 × 57.21
  4. Step 4: Simplify right side
    64.65x = 5,097.41
  5. Step 5: Solve for x
    x = 5,097.41/64.65
  6. Step 6: Final answer
    x = 78.85

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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.