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Finding the Fourth Proportional to 65.09, 89.78 and 56.90

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Solution

The fourth proportional to 65.09, 89.78 and 56.90 is: 78.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    65.09 : 89.78 = 56.90 : x
  2. Step 2: Convert to fraction form
    65.09/89.78 = 56.90/x
  3. Step 3: Cross multiply
    65.09x = 89.78 × 56.90
  4. Step 4: Simplify right side
    65.09x = 5,108.42
  5. Step 5: Solve for x
    x = 5,108.42/65.09
  6. Step 6: Final answer
    x = 78.48

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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.