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Finding the Fourth Proportional to 125.28, 172.80 and 90.45

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Solution

The fourth proportional to 125.28, 172.80 and 90.45 is: 124.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.28 : 172.80 = 90.45 : x
  2. Step 2: Convert to fraction form
    125.28/172.80 = 90.45/x
  3. Step 3: Cross multiply
    125.28x = 172.80 × 90.45
  4. Step 4: Simplify right side
    125.28x = 15,629.76
  5. Step 5: Solve for x
    x = 15,629.76/125.28
  6. Step 6: Final answer
    x = 124.76

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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.