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Finding the Fourth Proportional to 125.12, 172.80 and 99.20

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Solution

The fourth proportional to 125.12, 172.80 and 99.20 is: 137.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.12 : 172.80 = 99.20 : x
  2. Step 2: Convert to fraction form
    125.12/172.80 = 99.20/x
  3. Step 3: Cross multiply
    125.12x = 172.80 × 99.20
  4. Step 4: Simplify right side
    125.12x = 17,141.76
  5. Step 5: Solve for x
    x = 17,141.76/125.12
  6. Step 6: Final answer
    x = 137.00

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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.