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Finding the Fourth Proportional to 156, 215.28 and 87

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Solution

The fourth proportional to 156, 215.28 and 87 is: 120.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    156 : 215.28 = 87 : x
  2. Step 2: Convert to fraction form
    156/215.28 = 87/x
  3. Step 3: Cross multiply
    156x = 215.28 × 87
  4. Step 4: Simplify right side
    156x = 18,729.36
  5. Step 5: Solve for x
    x = 18,729.36/156
  6. Step 6: Final answer
    x = 120.06

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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.