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Finding the Fourth Proportional to 65.39, 90.21 and 39.15

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Solution

The fourth proportional to 65.39, 90.21 and 39.15 is: 54.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.39 : 90.21 = 39.15 : x
  2. Step 2: Convert to fraction form
    65.39/90.21 = 39.15/x
  3. Step 3: Cross multiply
    65.39x = 90.21 × 39.15
  4. Step 4: Simplify right side
    65.39x = 3,531.72
  5. Step 5: Solve for x
    x = 3,531.72/65.39
  6. Step 6: Final answer
    x = 54.01

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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.