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Finding the Fourth Proportional to 90.65, 124.78 and 64.73

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Solution

The fourth proportional to 90.65, 124.78 and 64.73 is: 89.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.65 : 124.78 = 64.73 : x
  2. Step 2: Convert to fraction form
    90.65/124.78 = 64.73/x
  3. Step 3: Cross multiply
    90.65x = 124.78 × 64.73
  4. Step 4: Simplify right side
    90.65x = 8,077.01
  5. Step 5: Solve for x
    x = 8,077.01/90.65
  6. Step 6: Final answer
    x = 89.10

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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.