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Finding the Fourth Proportional to 100.49, 138.70 and 56.85

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Solution

The fourth proportional to 100.49, 138.70 and 56.85 is: 78.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.49 : 138.70 = 56.85 : x
  2. Step 2: Convert to fraction form
    100.49/138.70 = 56.85/x
  3. Step 3: Cross multiply
    100.49x = 138.70 × 56.85
  4. Step 4: Simplify right side
    100.49x = 7,884.12
  5. Step 5: Solve for x
    x = 7,884.12/100.49
  6. Step 6: Final answer
    x = 78.46

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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.