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Finding the Fourth Proportional to 99.90, 137.90 and 79.22

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Solution

The fourth proportional to 99.90, 137.90 and 79.22 is: 109.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.90 : 137.90 = 79.22 : x
  2. Step 2: Convert to fraction form
    99.90/137.90 = 79.22/x
  3. Step 3: Cross multiply
    99.90x = 137.90 × 79.22
  4. Step 4: Simplify right side
    99.90x = 10,923.35
  5. Step 5: Solve for x
    x = 10,923.35/99.90
  6. Step 6: Final answer
    x = 109.34

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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.