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Finding the Fourth Proportional to 142.40, 196.42 and 87.12

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Solution

The fourth proportional to 142.40, 196.42 and 87.12 is: 120.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.40 : 196.42 = 87.12 : x
  2. Step 2: Convert to fraction form
    142.40/196.42 = 87.12/x
  3. Step 3: Cross multiply
    142.40x = 196.42 × 87.12
  4. Step 4: Simplify right side
    142.40x = 17,112.11
  5. Step 5: Solve for x
    x = 17,112.11/142.40
  6. Step 6: Final answer
    x = 120.17

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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.