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Finding the Fourth Proportional to 123.09, 169.78 and 99.80

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Solution

The fourth proportional to 123.09, 169.78 and 99.80 is: 137.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.09 : 169.78 = 99.80 : x
  2. Step 2: Convert to fraction form
    123.09/169.78 = 99.80/x
  3. Step 3: Cross multiply
    123.09x = 169.78 × 99.80
  4. Step 4: Simplify right side
    123.09x = 16,944.04
  5. Step 5: Solve for x
    x = 16,944.04/123.09
  6. Step 6: Final answer
    x = 137.66

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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.