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Finding the Fourth Proportional to 83.90, 115.90 and 64.74

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Solution

The fourth proportional to 83.90, 115.90 and 64.74 is: 89.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.90 : 115.90 = 64.74 : x
  2. Step 2: Convert to fraction form
    83.90/115.90 = 64.74/x
  3. Step 3: Cross multiply
    83.90x = 115.90 × 64.74
  4. Step 4: Simplify right side
    83.90x = 7,503.37
  5. Step 5: Solve for x
    x = 7,503.37/83.90
  6. Step 6: Final answer
    x = 89.43

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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.