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Finding the Fourth Proportional to 66.40, 91.68 and 61.60

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Solution

The fourth proportional to 66.40, 91.68 and 61.60 is: 85.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.40 : 91.68 = 61.60 : x
  2. Step 2: Convert to fraction form
    66.40/91.68 = 61.60/x
  3. Step 3: Cross multiply
    66.40x = 91.68 × 61.60
  4. Step 4: Simplify right side
    66.40x = 5,647.49
  5. Step 5: Solve for x
    x = 5,647.49/66.40
  6. Step 6: Final answer
    x = 85.05

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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.