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Finding the Fourth Proportional to 66.40, 90.68 and 65.68

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Solution

The fourth proportional to 66.40, 90.68 and 65.68 is: 89.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.40 : 90.68 = 65.68 : x
  2. Step 2: Convert to fraction form
    66.40/90.68 = 65.68/x
  3. Step 3: Cross multiply
    66.40x = 90.68 × 65.68
  4. Step 4: Simplify right side
    66.40x = 5,955.86
  5. Step 5: Solve for x
    x = 5,955.86/66.40
  6. Step 6: Final answer
    x = 89.70

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.