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Finding the Fourth Proportional to 66.61, 99.75 and 42.15

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Solution

The fourth proportional to 66.61, 99.75 and 42.15 is: 63.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    66.61 : 99.75 = 42.15 : x
  2. Step 2: Convert to fraction form
    66.61/99.75 = 42.15/x
  3. Step 3: Cross multiply
    66.61x = 99.75 × 42.15
  4. Step 4: Simplify right side
    66.61x = 4,203.86
  5. Step 5: Solve for x
    x = 4,203.86/66.61
  6. Step 6: Final answer
    x = 63.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.