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Finding the Fourth Proportional to 100.49, 138.53 and 78.62

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Solution

The fourth proportional to 100.49, 138.53 and 78.62 is: 108.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.49 : 138.53 = 78.62 : x
  2. Step 2: Convert to fraction form
    100.49/138.53 = 78.62/x
  3. Step 3: Cross multiply
    100.49x = 138.53 × 78.62
  4. Step 4: Simplify right side
    100.49x = 10,890.84
  5. Step 5: Solve for x
    x = 10,890.84/100.49
  6. Step 6: Final answer
    x = 108.38

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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.