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Finding the Fourth Proportional to 100.20, 138.25 and 56.53

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Solution

The fourth proportional to 100.20, 138.25 and 56.53 is: 78.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.20 : 138.25 = 56.53 : x
  2. Step 2: Convert to fraction form
    100.20/138.25 = 56.53/x
  3. Step 3: Cross multiply
    100.20x = 138.25 × 56.53
  4. Step 4: Simplify right side
    100.20x = 7,815.27
  5. Step 5: Solve for x
    x = 7,815.27/100.20
  6. Step 6: Final answer
    x = 78.00

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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.