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Finding the Fourth Proportional to 125.40, 172.88 and 100.80

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Solution

The fourth proportional to 125.40, 172.88 and 100.80 is: 138.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.40 : 172.88 = 100.80 : x
  2. Step 2: Convert to fraction form
    125.40/172.88 = 100.80/x
  3. Step 3: Cross multiply
    125.40x = 172.88 × 100.80
  4. Step 4: Simplify right side
    125.40x = 17,426.30
  5. Step 5: Solve for x
    x = 17,426.30/125.40
  6. Step 6: Final answer
    x = 138.97

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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.