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Finding the Fourth Proportional to 156.12, 215.42 and 89.72

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Solution

The fourth proportional to 156.12, 215.42 and 89.72 is: 123.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.12 : 215.42 = 89.72 : x
  2. Step 2: Convert to fraction form
    156.12/215.42 = 89.72/x
  3. Step 3: Cross multiply
    156.12x = 215.42 × 89.72
  4. Step 4: Simplify right side
    156.12x = 19,327.48
  5. Step 5: Solve for x
    x = 19,327.48/156.12
  6. Step 6: Final answer
    x = 123.80

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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.