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Finding the Fourth Proportional to 156.78, 216.32 and 90.39

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Solution

The fourth proportional to 156.78, 216.32 and 90.39 is: 124.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.78 : 216.32 = 90.39 : x
  2. Step 2: Convert to fraction form
    156.78/216.32 = 90.39/x
  3. Step 3: Cross multiply
    156.78x = 216.32 × 90.39
  4. Step 4: Simplify right side
    156.78x = 19,553.39
  5. Step 5: Solve for x
    x = 19,553.39/156.78
  6. Step 6: Final answer
    x = 124.72

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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.