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Finding the Fourth Proportional to 87.40, 120.65 and 65.25

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Solution

The fourth proportional to 87.40, 120.65 and 65.25 is: 90.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.40 : 120.65 = 65.25 : x
  2. Step 2: Convert to fraction form
    87.40/120.65 = 65.25/x
  3. Step 3: Cross multiply
    87.40x = 120.65 × 65.25
  4. Step 4: Simplify right side
    87.40x = 7,872.58
  5. Step 5: Solve for x
    x = 7,872.58/87.40
  6. Step 6: Final answer
    x = 90.08

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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.