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Finding the Fourth Proportional to 125.28, 172.48 and 86.40

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Solution

The fourth proportional to 125.28, 172.48 and 86.40 is: 118.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.28 : 172.48 = 86.40 : x
  2. Step 2: Convert to fraction form
    125.28/172.48 = 86.40/x
  3. Step 3: Cross multiply
    125.28x = 172.48 × 86.40
  4. Step 4: Simplify right side
    125.28x = 14,902.27
  5. Step 5: Solve for x
    x = 14,902.27/125.28
  6. Step 6: Final answer
    x = 118.95

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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.