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Finding the Fourth Proportional to 99.78, 137.67 and 64.35

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Solution

The fourth proportional to 99.78, 137.67 and 64.35 is: 88.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.78 : 137.67 = 64.35 : x
  2. Step 2: Convert to fraction form
    99.78/137.67 = 64.35/x
  3. Step 3: Cross multiply
    99.78x = 137.67 × 64.35
  4. Step 4: Simplify right side
    99.78x = 8,859.06
  5. Step 5: Solve for x
    x = 8,859.06/99.78
  6. Step 6: Final answer
    x = 88.79

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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.