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Finding the Fourth Proportional to 100.30, 138.42 and 56.65

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Solution

The fourth proportional to 100.30, 138.42 and 56.65 is: 78.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.30 : 138.42 = 56.65 : x
  2. Step 2: Convert to fraction form
    100.30/138.42 = 56.65/x
  3. Step 3: Cross multiply
    100.30x = 138.42 × 56.65
  4. Step 4: Simplify right side
    100.30x = 7,840.80
  5. Step 5: Solve for x
    x = 7,840.80/100.30
  6. Step 6: Final answer
    x = 78.18

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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.