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Finding the Fourth Proportional to 99.86, 137.88 and 64.91

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Solution

The fourth proportional to 99.86, 137.88 and 64.91 is: 89.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.86 : 137.88 = 64.91 : x
  2. Step 2: Convert to fraction form
    99.86/137.88 = 64.91/x
  3. Step 3: Cross multiply
    99.86x = 137.88 × 64.91
  4. Step 4: Simplify right side
    99.86x = 8,950.14
  5. Step 5: Solve for x
    x = 8,950.14/99.86
  6. Step 6: Final answer
    x = 89.62

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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.