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Finding the Fourth Proportional to 85.30, 128.01 and 31.24

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Solution

The fourth proportional to 85.30, 128.01 and 31.24 is: 46.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.30 : 128.01 = 31.24 : x
  2. Step 2: Convert to fraction form
    85.30/128.01 = 31.24/x
  3. Step 3: Cross multiply
    85.30x = 128.01 × 31.24
  4. Step 4: Simplify right side
    85.30x = 3,999.03
  5. Step 5: Solve for x
    x = 3,999.03/85.30
  6. Step 6: Final answer
    x = 46.88

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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.