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Finding the Fourth Proportional to 85.64, 128.50 and 47.09

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Solution

The fourth proportional to 85.64, 128.50 and 47.09 is: 70.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.64 : 128.50 = 47.09 : x
  2. Step 2: Convert to fraction form
    85.64/128.50 = 47.09/x
  3. Step 3: Cross multiply
    85.64x = 128.50 × 47.09
  4. Step 4: Simplify right side
    85.64x = 6,051.27
  5. Step 5: Solve for x
    x = 6,051.27/85.64
  6. Step 6: Final answer
    x = 70.66

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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.