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Finding the Fourth Proportional to 108.40, 161.76 and 90.40

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Solution

The fourth proportional to 108.40, 161.76 and 90.40 is: 134.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.40 : 161.76 = 90.40 : x
  2. Step 2: Convert to fraction form
    108.40/161.76 = 90.40/x
  3. Step 3: Cross multiply
    108.40x = 161.76 × 90.40
  4. Step 4: Simplify right side
    108.40x = 14,623.10
  5. Step 5: Solve for x
    x = 14,623.10/108.40
  6. Step 6: Final answer
    x = 134.90

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.