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Finding the Fourth Proportional to 102.40, 140.40 and 100.80

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Solution

The fourth proportional to 102.40, 140.40 and 100.80 is: 138.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.40 : 140.40 = 100.80 : x
  2. Step 2: Convert to fraction form
    102.40/140.40 = 100.80/x
  3. Step 3: Cross multiply
    102.40x = 140.40 × 100.80
  4. Step 4: Simplify right side
    102.40x = 14,152.32
  5. Step 5: Solve for x
    x = 14,152.32/102.40
  6. Step 6: Final answer
    x = 138.21

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.