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Finding the Fourth Proportional to 90, 124.20 and 51.20

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Solution

The fourth proportional to 90, 124.20 and 51.20 is: 70.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 124.20 = 51.20 : x
  2. Step 2: Convert to fraction form
    90/124.20 = 51.20/x
  3. Step 3: Cross multiply
    90x = 124.20 × 51.20
  4. Step 4: Simplify right side
    90x = 6,358.42
  5. Step 5: Solve for x
    x = 6,358.42/90
  6. Step 6: Final answer
    x = 70.65

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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.