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Finding the Fourth Proportional to 85.51, 128.09 and 65.16

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Solution

The fourth proportional to 85.51, 128.09 and 65.16 is: 97.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.51 : 128.09 = 65.16 : x
  2. Step 2: Convert to fraction form
    85.51/128.09 = 65.16/x
  3. Step 3: Cross multiply
    85.51x = 128.09 × 65.16
  4. Step 4: Simplify right side
    85.51x = 8,345.38
  5. Step 5: Solve for x
    x = 8,345.38/85.51
  6. Step 6: Final answer
    x = 97.60

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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.