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Finding the Fourth Proportional to 156.45, 215.67 and 128.77

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Solution

The fourth proportional to 156.45, 215.67 and 128.77 is: 177.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.45 : 215.67 = 128.77 : x
  2. Step 2: Convert to fraction form
    156.45/215.67 = 128.77/x
  3. Step 3: Cross multiply
    156.45x = 215.67 × 128.77
  4. Step 4: Simplify right side
    156.45x = 27,771.83
  5. Step 5: Solve for x
    x = 27,771.83/156.45
  6. Step 6: Final answer
    x = 177.51

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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.